The invention discloses a concrete waterproof agent. The concrete waterproof agent is prepared from, by mass, 50%-60% of a methanesiliconic acid sodium salt-calcium hydroxide complex solution, 20%-30%of a sodium silicate solution, 1%-3% of sodium citrate, 2%-3% of triethanolamine, 2%-5% of hydroxypropyl methyl cellulose, 0.3%-0.6% of thickening agent 80A51, 2%-3% of pectin, 5% of JX anti-crack siliceous waterproof agent, 1%-2% of aluminum sulfide, 0.2%-0.5% of tert-Butyldiphenylsilane and 1%-3% of rosinyl hyperbranched epoxy resin. According to the concrete waterproof agent, aluminum sulfide,tert-Butyldiphenylsilane, rosinyl hyperbranched epoxy resin, sodium silicate and the methanesiliconic acid sodium salt-calcium hydroxide complex solution are mixed with other raw materials, a cross-linked network structure is formed through the rosinyl hyperbranched epoxy resin at the early stage and can proof water, enough time is left for crystal growth, and the problems that the waterproof effect is slow, and long-time maintenance is required are solved.