In order to solve the problem of larger internal resistance of thin-film thermoelectric generator (TEG) in series, which could influence the output power and restrict the application, the in-plane carbon nanotube (CNT) TEG in parallel was ingeniously researched. Utilizing the parameters of output power, conversion and energy efficiencies, the ideal and actual models of TEG in parallel were established, respectively. The thermal conduction insulating layer was taken into account, which could provide the theoretical guidance for the experimental test and engineering applications. The CNT films were prepared by the floating-catalyst chemical vapor deposition (CVD), and the experiment and properties of TEG based on CNT films were investigated. The testing circuits of conventional and gas TEGs were designed, and the output powers of the serial and parallel connecting types were tested and compared. The correctness of theoretical model and numerical analysis was proved to be valid. The novel method could effectively enhance the output power, extend the applied range of TEG in MEMS/NEMS and had a fine prospect.