The utility model relates to a protection circuit in a motor main circuit, particularly provides an electrical overload protection circuit of a mixing station, and successfully solves the problem that a proportioning system of the existing concrete mixing station is unreasonable in circuit protection structure. The electrical overload protection circuit of a mixing station comprises a normally open contact of a first contactor KM1, a normally open contact of a second contactor KM2, a normally open contact of a third contactor KM3, a normally open contact of a fourth contactor KM4, a first thermal relay FR1, a second thermal relay FR2 and a circuit breaker QF1. According to the utility model, the thermal relays are added in the main circuit, and motors with different powers are separated into different branch circuits, thereby preventing the working currents of the motors with different powers from being affected by each other and successfully solving the problem that a proportioning system of the existing concrete mixing station is unreasonable in circuit protection structure.