As a special language phenomenon, metaphor expresses non-literal meaning, which increases the difficulty of exploring its truth condition. In the 1990s, Glucksberg et al. proposed the Category Attribution Theory, interpreting the understanding of metaphorical sentences as a category attribution judgment. According to the theory, metaphor has two potential referential objects: a literal referential, and a category of things or situations represented by this metaphor. Genabith later described this class category based on the standard type theory which uses a high-order logic based on the λ calculus. This was one approach to the semantic truth condition of metaphorical statements. In traditional logical semantics, the generations of grammar and semantics meet the principle of combination, namely, in the form of one-to-one correspondence. But for metaphorical sentences, this syntactic-semantic correspondence in generation raises questions. It is because in the traditional way, we can only get the literal meaning of the statement rather than what we really intend to express. Therefore, we need another combination of categories to achieve the generation of metaphorical meaning, that is, metaphorical sentences are given different categories by their unique tags. As pointed out by truth conditional pragmatics, the truth condition of a statement often goes beyond the semantic level and involves more complicated pragmatic factors. Therefore, meaning is not a simple combination of separate parts while we are taking context into consideration. Rather, meaning is modulated by the context. In the framework of category type theory which connects the three dimensions of syntax, semantics and pragmatics, this paper attempts to extend the analysis of semantic truth conditions to syntactic and pragmatic levels, with the aim of presenting the interweaving and interaction of the three to better replicate the generation and understanding of metaphorical meaning. From the perspective of categorical grammar, in metaphorical sentences, vocabulary is given new categories as well as corresponding semantic types. The type of source domain is transformed from a set of individuals into a set of properties, with an explicit or implicit metaphorical marker whose type is a function mapping a set of properties to a set of individuals. The function extracts context-dependent properties in the source domain. If the object in the target domain satisfies this extracted property, the metaphorical statement is true. Take the metaphorical sentence ″A is B″ as an example. When Source Domain B is promoted from a set of objects to a set of properties, the metaphorical token ″is″ is a function restricted by context mapping a property set to an individual set. Intuitively, its role is to choose a certain property with a high degree of context fusion among the properties of B. Finally, the truth condition for ″A is B″ becomes: A is B=1 iff A, where is a certain property of B. This means that the semantic change can be realized by giving a new category to each component in the sentence and changing the corresponding semantic type. Thereby we get the truth condition of metaphor that is consistent with the classical interpretation. At the same time, the special position of context in metaphorical understanding is considered. Our approach is expected to refine the theory of truth conditional pragmatics and systematically answer the question of ″How does the context-to-semantic adaptation proceed″. It also disassembles the metaphorical understanding process that is instantaneously completed in real communication, and gives an answer to the question of ″How do we understand metaphor″ from the perspective of logical semantics.