The invention discloses a compound cultivation method for grafting tomato on potato. According to the compound cultivation method for grafting the tomato on the potato, soil preparation, bedding and deep tillage are carried out, base fertilizer is applied enough; tomato seeds are sowed on every other bed, disinfected potato seeds are sowed onto the other beds 12-15 days after the tomato seeds are sowed, when the height of each tomato grafting seedling reaches 8-10cm after 40-55 days, or when each tomato grafting seedling has four leaves, grafting is carried out; the top stem section, with a length of 1.5-2.5cm, of each tomato grafting seedling is taken, and the tip of each top stem section is sharpened to be wedged, a grafting knife is used for carrying out downwards deep cutting from the top of each potato rootstock seedling, each tomato grafting seedling is inserted into each cut, soil preparation and deep tillage are carried out on the field beds planted with the tomato grafting seedlings again, and disinfected potato seeds are sowed again on the field beds. The compound cultivation method for grafting the tomato on the potato combines cultivation of the potatoes and cultivation of the tomatoes into a whole, and economic value of the tomatoes are improved through effective use of potato resources. As certified, the compound cultivation method for grafting the tomato on the potato improves economic benefit, the output value, per mu, of the potato is larger than two thousand yuan, the output value, per mu, of the tomato is more than fifteen thousand yuan, and the economic character of the tomato is effectively improved.