Nd3+ complex doped polymer liquid laser have been demonstrated and the threshold of the laser was also calculated. The calculation results that a laser media with 2mm length is suitable for low threshold laser oscillation. We obtained the slope efficiency of 20% and the maximum output energy of 5.3mJ at the pumping energy of 31mJ by the method of the side pumping. To the best of knowledge, this is the highest slope efficiency of the bulky laser using Nd3+ complex.