The invention discloses a working condition control device in a pump turbine speed adjusting system and a control method of the working condition control device. The device comprises a main distributing valve, a shuttle valve cartridge valve set, a cartridge valve, a working condition selecting valve, a servomotor, a sequence closing valve set, a guide vane control ring, a check valve, an electro-hydraulic control oil input port, a pressure oil input port, three throttling oil discharging ports, a control oil input port and a throttle valve. Selection of working conditions is conducted through the working condition selecting valve, and then when load shedding is conducted under the situation that a pump turbine unit breaks down, sequence closing of guide vanes under the working condition is achieved through cooperation of the main distributing valve, the shuttle valve cartridge valve set, the cartridge valve and the like. According to the working condition control device and the control method, the working condition selecting valve and the shuttle valve cartridge valve set are additionally arranged in the device creatively, different closing rules of the same device under different working conditions are achieved, rising of the load shedding pressure of the unit under multiple working conditions is reduced, and the running section and range of the unit are enlarged; and protection on the unit is reliably improved, and the beneficial effects that the structure is simple, cost is low and control is accurate are achieved.