In order to obtain deep ultraviolet (UV) ultrashort pulses with large energy, deep UV femtosecond seed light is amplified by an ArF excimer amplifier. By measuring the seed light signal and the fluorescence signal of the excimer amplifier, the effect of the delay between the seed light signal and the amplifier discharge signal on the single amplification characteristics of the pulse was investigated under different environments. The results show that the amplification system achieves precise synchronization of seed light and excimer amplifier with low jitter, the maximum pulse energy in air and nitrogen is 197.2 μJ and 312.6 μJ, respectively, and the pulse spreading in nitrogen environment is reduced by 99.2 fs on average compared with in air. It is proved that compared to air environment, nitrogen environment can effectively reduce the energy decay and pulse spreading of deep UV ultrashort pulses, and synchronous jitter has less influence on amplification characteristics.