Safety device for hydraulic jacking system of tower crane

The utility model provides a safety device for a hydraulic jacking system of a tower crane. The safety device comprises a jacking oil cylinder (11), a pressure relief operating valve (92), a one-way valve I (91), a counterbalance valve (7) and an operating valve (6), wherein the pressure relief operating valve (92) is connected in parallel with the one-way valve I (91), and then an output end of the pressure relief operating valve (92) is communicated with an input end of the jacking oil cylinder (11), an output end of the pressure relief operating valve (92) is communicated with the operating valve (6), an output end of the jacking oil cylinder (11) is communicated with the operating valve (6) through the counterbalance valve (7), an input end of the one-way valve I (91) is communicated with the output end of the jacking oil cylinder (11), and therefore the height of a tower cap is reduced and the safety of the crane is improved.