The invention discloses a feed suitable for feeding spodoptera frugiperda larvae and a preparation method thereof. The preparation method of the feed comprises the steps that part of water is heated until boiling, agar is added, and stirring is carried out until the agar is dissolved; part of water is added into a mixture, then corn flour, wheat bran, beer yeast powder, glucose and a preservativeare added, uniform stirring is carried out, then cooling is carried out to the room temperature, then cholesterol, decavitamin powder, streptomycin, formaldehyde and honey are added, uniform stirringis carried out, and the feed is obtained. The feed is used for feeding the spodoptera frugiperda larvae, the spodoptera frugiperda larvae are fond of eating, biological indicators such as development,survival rate, pupation rate and eclosion rate have no significant difference with those of natural feed such as maize leaves, the feed has low cost and longer shelf life, generations do not need toreplace the feed, the feed is more economical, the problem is solved that the spodoptera frugiperda cannot be subcultured annually due to shortage of the natural feed caused by the seasonal change, and large-batch annual subculture of standard insect sources is achieved.