The invention relates to the technical field of measuring devices, in particular to an assembly system and assembling method based on binocular vision. The invention aims at solving the problems that measuring cannot be conducted in a narrow and small space by utilizing visual three-dimensional measurement technology and measuring steps are complicated under the condition that multiple posts are needed to be measured. The assembly system comprises a collection part, a data processing unit and an executing mechanism. The collection part is used for synchronously collecting first post information of an assembly part to be assembled and second post information of a butt joint part; the data processing unit is used for calculating result post information between the assembly part to be assembled and the butt joint part based on the first post information and the second post information; the executing mechanism is used for installing the assembly part to be assembled to the joint butt part based on the result post information. The data processing unit calculates the result information based on the first post information and the second post information synchronously collected by the collection part, and the executing mechanism can efficiently achieve the high-precision assembling between the assembly part to be assembled and the joint butt part based on the result information.