The production wells of PL oilfield mainly adopt 177.8 millimeters casing, and the restriction of borehole size leads to the failure of conventional separate-layered production process. However, cable-controlled intelligent separate-layered production technology which is a new technology to solve the separate-layered production of production wells, exists the problem of pipe string structure. In view of this, the downhole cable wet docking assembly has been developed. The assembly is composed of release connector and cable docking pin. In operation, the release connector can be released by hydraulic ball after the separate-layered string has been run into well. The cable butt male is carried by the production string of electric pump to realize wet docking with the release connector. After docking, it can meet the requirements of sealing insulation and power supply communication under high temperature, high pressure and high humidity environment underground. The results of indoor test and field application show that the assembly has reasonable design and reliable docking, can maintain long-term power supply and communication and meets separate-layered production requirements of 177.8 millimeters casing small wells in PL oilfield. The study results can provide technology support for separate-layered production of the large inclined well and horizontal well.