In order to monitor and adjust the process of selective laser melting, a set of molten pool image acquisition system with coaxial high-speed camera was established, and the online real-time monitoring and evaluation method of 10 kHz high-speed molten pool image was studied. The finite element modeling was completed, and the normal morphology of the molten pool was analyzed by simulation. The high-speed image acquisition and processing system was developed based on FPGA, and the real-time analysis, processing and output of 10 kHz images were realized. The high-speed video system is integrated on the laser powder bed fusion (LPBF) technology, and the experimental test and verification are carried out. The experimental results show that the system can monitor and output the evaluation parameters of the molten pool in real time, which lays a technical foundation for the closed-loop control of selective laser melting.