In the process of fused deposition modeling，the interactive coupling effects of filling velocity with layer thickness and nozzle temperature affects the forming accuracy of the parts． In this paper，a double-variate experi-ment on two types of PLA samples was conducted． Taking dimensional accuracy as the assessment index，ANOVA and multivariate nonlinear regression analysis were used to study the coupling mechanism among filling velocity，layer thickness and nozzle temperature．Results show that: (1) the interactive coupling effect of filling velocity with layer thickness and nozzle temperature has a significant impact on the dimensional accuracy of parts; (2) the di-mensional size and shape of parts could affect the coupling control function construction of filling velocity，layer thickness and nozzle temperature; and (3) by employing the coupling control method of filling velocity with layer thickness and nozzle temperature，dimensional deviation of FDM parts can be effectively improved and stabilized．