A pitch control method based on a clearance of a wind turbine, wherein the wind turbine comprises at least two blades, and the pitch control method comprises: obtaining a clearance of the wind turbine in real time; dynamically adjusting an additional pitch angle value of each blade according to the clearance obtained in real time; determining, for each blade, a pitch angle control value of the blade according to an existing pitch angle given value of the blade and the additional pitch angle value of the blade; and applying, simultaneously for each blade, the determined pitch angle control value to the corresponding blade of the wind turbine to control all blades to perform a pitch action simultaneously, so as to adjust the clearance of the wind turbine; characterized in that the step of dynamically adjusting the additional pitch angle value of each blade according to the clearance obtained in real time comprises: determining a clearance interval corresponding to the clearance obtained in real time; triggering an additional pitch angle protection function and gradually increasing the additional pitch angle value within a first preset time, to reach a preset additional angle value, if the determined clearance interval is a second clearance interval; and in the process of gradually increasing the additional pitch angle value or after the additional pitch angle value reaches the preset additional angle value, maintaining a current additional pitch angle value invariant if the clearance interval corresponding to the clearance obtained in real time changes from the second clearance interval to a third clearance interval, and gradually decreasing the current additional pitch angle value within a second preset time, if the clearance interval corresponding to the clearance obtained in real time changes from the third clearance interval to a fourth clearance interval, wherein a time length of the second preset time is greater than a time length of the first preset time. obtaining a clearance of the wind turbine in real time; dynamically adjusting an additional pitch angle value of each blade according to the clearance obtained in real time; determining, for each blade, a pitch angle control value of the blade according to an existing pitch angle given value of the blade and the additional pitch angle value of the blade; and applying, simultaneously for each blade, the determined pitch angle control value to the corresponding blade of the wind turbine to control all blades to perform a pitch action simultaneously, so as to adjust the clearance of the wind turbine; characterized in that the step of dynamically adjusting the additional pitch angle value of each blade according to the clearance obtained in real time comprises: determining a clearance interval corresponding to the clearance obtained in real time; triggering an additional pitch angle protection function and gradually increasing the additional pitch angle value within a first preset time, to reach a preset additional angle value, if the determined clearance interval is a second clearance interval; and in the process of gradually increasing the additional pitch angle value or after the additional pitch angle value reaches the preset additional angle value, maintaining a current additional pitch angle value invariant if the clearance interval corresponding to the clearance obtained in real time changes from the second clearance interval to a third clearance interval, and gradually decreasing the current additional pitch angle value within a second preset time, if the clearance interval corresponding to the clearance obtained in real time changes from the third clearance interval to a fourth clearance interval, wherein a time length of the second preset time is greater than a time length of the first preset time. determining a clearance interval corresponding to the clearance obtained in real time; triggering an additional pitch angle protection function and gradually increasing the additional pitch angle value within a first preset time, to reach a preset additional angle value, if the determined clearance interval is a second clearance interval; and in the process of gradually increasing the additional pitch angle value or after the additional pitch angle value reaches the preset additional angle value, maintaining a current additional pitch angle value invariant if the clearance interval corresponding to the clearance obtained in real time changes from the second clearance interval to a third clearance interval, and gradually decreasing the current additional pitch angle value within a second preset time, if the clearance interval corresponding to the clearance obtained in real time changes from the third clearance interval to a fourth clearance interval, wherein a time length of the second preset time is greater than a time length of the first preset time.