The utility model provides a variable pitch system of a wind power generating set and the wind power generating set. The variable pitch system of the wind power generating set comprises an air compressor, a one-way valve, a compressed air storage tank, an electromagnetic valve, a pneumatic motor and a variable pitch speed reducer. The air compressor sends compressed air to the compressed air storage tank for storing through the one-way valve. When an external power source of the wind power generating set breaks down, the electromagnetic valve is turned on, the compressed air stored in the compressed air storage tank is sent to the pneumatic motor, the pneumatic motor rotates under the driving of the compressed air, so that the variable pitch speed reducer is driven to rotate blades to a feathering position. The variable pitch system of the wind power generating set can enable a variable pitch system structure to be simplified substantially, reliability of products is substantially improved, and galloping accidents caused by failures of the variable pitch system can be reduced to the largest extent.