In order to study the low-power pulsed laser-induced double arc coupling discharge effect and improve the energy utilization rate of the hybrid heat source, this paper adopts different heat source arrangement modes (laser-guided, double arc-guided) and conducts welding experiments under different Dla (distance between laser beam and two tungsten electrodes). The high-speed camera and spectral diagnostic system are used to monitor the dynamic behavior of arc plasma information, molten pool, and keyhole in real-time and calculate the characteristics of electron temperature and electron density of the coupled plasma. The physical model is established to analyze and discuss the time characteristics and energy distribution of coupled discharge. The results show that according to the different Dla, the hybrid heat source has three different coupling effects: laser and double arc interfere with each other, laser and double arc good coupling, laser and double arc no significant effect. When the laser and the double arc have a good coupling state, the coupled plasma has a lower electron temperature and a higher electron density. At this time, the Marangoni force and arc pressure on the liquid metal in the laser keyhole is enough to overcome its own gravity. The keyhole has existed for a long time, which is conducive to the extension of the laser-arc coupling discharge effect and improves the energy utilization efficiency of the hybrid heat source. Compared with the laser-guided mode, the double arc-guided mode has a larger coupling discharge period and duty cycle, and the energy density of the conductive region in the center of the keyhole increases by 14.4 %, which is beneficial to improve the energy utilization efficiency of the hybrid heat source and obtain a larger penetration depth.