Penicillin producing strain ,Penicillium chrysogenum, Pc05 as the starting strain was mutated by low-temperature air plasma technology. As the result revealed, in 30 minutes, the survival rate of spores followed the saddle-shaped curve. The positive mutants accounted for 44.19% of all mutants while the negative mutation was low. After primary and secondary screening, the mutant aPc051310 was obtained, and eventually its penicillin titer increased 42.1% compared with that of starting strain. Synergetic effect between chemical reactive species and charged particles was considered as the main mutation mechanism involved in low temperature air plasma. All the results have been proved that as a new industrial microbial strains mutation method, low temperature air plasma has potential applications.