Abstract: Taking waste rock wool with different particle sizes（1,2,3 cm） as the matrix, a pot experiment was carried out.The physical and chemical properties of old rock wool mat and old rock wool matrix with different particle sizes and their effects on vegetable growth and yield were studied, in order to solve the treatment problem of greenhouse waste rock wool and realize effective reuse of rockwool with low cost.The results showed that the physical and chemical properties of the matrix could be effectively changed by the cutting and recombination method.Field experiments showed that cutting recombinant rock wool could promote the growth of pepper and increase the yield by 5.5%-28.9%.However, the yield of single crop of lettuce was not affected.Therefore, it was feasible to adjust the physical and chemical properties of substrates by cutting and recombining to realize the reuse of waste rock wool substrates to grow vegetables.Two sizes of leaf vegetables could be grown, and the appropriate size of pepper was 2 cm×2 cm×2 cm.The results provided an effective method and guidance for clarifying the change of physicochemical properties of old rock wool and solving the treatment and reuse of waste rock wool in greenhouse.