The invention discloses a synergistic bio-composite insecticidal pesticide for gardening and a preparation method thereof. The pesticide is prepared from, by weight, 16-25 parts of extract liquid of euphorbia helioscopia, 8-14 parts of bergenin std., 6-11 parts of extract of pyrethrum cinerariifolium, 7-11 parts of attapulgite powder, 3-5 parts of sophora flavescens alkaloids, 4-7 parts of chili,2-6 parts of folium artemisiae argyi, 15-21 parts of euphorbia nematocypha, 7-12 parts of tea saponin, and 6-12 parts of pumpkin leaves. In the invention, by means of effective ratio of the extract liquid of euphorbia helioscopia, the bergenin std., the extract of pyrethrum cinerariifolium, the attapulgite powder, the sophora flavescens alkaloids, the chili, the folium artemisiae argyi, the euphorbia nematocypha, the tea saponin and the pumpkin leaves, the pesticide is produced. The preparation method is simple. The pesticide has significant effect of killing pests and has no residue, is freeof polluting soil, water source and crops, can be degraded in natural environment, is free of damage on human and animals and generation of drug resistance in pests, is prepared from natural raw materials and is toxic-free, and has good insecticidal effect when being directly applied to flowers.