Disclosed are a method, a device, equipment and a medium for dynamic positioning of a semi-submersible offshore platform. The method includes: acquiring a real-time position of the platform; if the real-time position is different from a preset position, detecting an external force torque by a first torque detector; calculating a first target thrust produced by each of propellers, controlling the propellers to produce forces according to a first target thrust torque, and detecting an actual thrust torque; obtaining a fault condition of each of the propellers if the actual thrust torque is different from the first target thrust torque, indicating that the propellers have faults; recalculating a thrust of each of the propellers, a second target thrust torque, according to the fault condition, the external force torque and the preset formula set; and controlling each of the propellers to generate the thrust according to a corresponding second target thrust torque.