The time and intensity dependent characteristics of the amplified spontaneous emission (ASE) and the lasing of a copolymer in tetrahydrofuran (THF) solution, Poly[1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1,5-phenylene-1,2-ethenylene-3,5dimethoxy-1, 4-phenylene](CNMBC-Ph), were studied. By using Nd:YAG laser-streak camera system, we investigated the time behaviors of the ASE and the lasing of CNMBC-Ph pumped at various energies on picosecond time scale. Their real-time evolution of intensity-dependency reveals that the threshold and the time of the lasing generation are closely related to the temporal intensity of the pump light. The relationship between the threshold of pump energy and the duration of the pump light, spontaneous and the cross section of the stimulated emission were discussed.