Carbon black (CB) was functionalized by covalent bond using silane coupling agent KH550, and the carbon black before and after modification was investigated by FTIR, DLS and SEM. The results showed that the particle size of carbon black modified by KH550 was about 620nm and dispersed uniformly.CB/ WPU and KH550/CB/WPU conductive composites were prepared by solution blending and casting method. It was found that KH550/CB had better dispersibility in WPU matrix, which made the contact between conductive particles closer. When the addition amount was 3%, the conductivity was 1.79×10-3 S/m, which was 10 times higher than that of CB/WPU composites. The mechanical test showed that when the content was 2%, the tensile strength was 175% higher than that of CB/WPU composite.On this basis, the effects of different filling patterns and filling ratios on the electrical conductivity of KH550/CB/WPU composites were investigated by direct writing 3D printing. The results show that when the linear filling is selected and the filling rate is 80%, the conductivity is good, and the conductivity reaches 2.66×10-3 S/m.