The invention discloses application of L-proline in increasing blastospore quantity and mycelial biomass of Cordyceps sinensis. In order to solve the problem of how to increase mycelial biomass duringliquid fermentation of Cordyceps sinensis and the problem of how to acquire massive infection blastospores during artificial cultivation of entomogenous fungi with Cordyceps sinensis, L-proline is added to a Cordyceps sinensis medium to induce Cordyceps sinensis to efficiently produce blastospores; after Cordyceps sinensis spores are induced to the medium with the L-proline and cultured for 30 days, the quantity of blastospores is 1.49-5.26 times as high as that of a group with no addition; after 45 days of cultivation, the quantity of the blastospores is increased by 17-52.6 times; after 60days of cultivation, mycelial dry weight is increased by 15.67-66.44%. The blastospores for infecting Hepialus armoricanus so as to artificially cultivate entomogenous fungi with Cordyceps sinensis can be acquired more efficiently herein; the efficiency of acquiring mycelia by liquid fermentation of Cordyceps sinensis can be improved; artificial cultivation time of Cordyceps sinensis can be shortened; cultivation cost can be reduced.