The invention provides a preparation method of game fish triploid fries. The preparation method comprises the following steps of: hybridizing a rainbow trout female parent fish and an arctic char male parent fish; transferring fertilized ova which have been fertilized for 20 minutes under the condition of 7 DEG C into a water body of 26 DEG C and performing heat shock for 20 minutes; then transferring into a water body of 7 DEG C to hatch for about 60 days; and hatching fish fries from the fertilized ova, wherein the eyed rate of the fertilized ova in the hatching period is over 75 percent, the hatching rate of the fries reaches over 90 percent, and the triploid rate of the obtained fries is 90-95 percent through detection of a flow cytometer. According to the preparation method of game fish triploid fries provided by the invention, the problems of sexual precosity, size miniaturization, disease breeding and the like of bred individuals due to long-term close breeding and shortage of systematic breeding in the rainbow trout culturing process are relieved, meanwhile, the hybrid triploid has the two advantages of the hybridization and the triploid, the growth speed and the disease resistance are obviously superior to those of the conventional diploid rainbow trout, and the preparation method has higher economic benefit and market value.