The invention relates to a dynamic grid-connected system for a zero-transition process of a permanent magnet direct-drive fan. The system comprises a wind turbine generator system, a rectifier, an inverter, a filter and a grid-connected circuit breaker. The grid-connected circuit breaker and a zero-crossing dynamic grid-connected electric power electronic switch module are connected in parallel. The zero-crossing dynamic grid-connected electric power electronic switch module comprises a power electronic switch, a zero-transition dynamic grid-connected control system and a signal system. The data port of the zero-transition dynamic grid-connected control system is respectively connected with the power electronic switch and the signal system. The data input port of the signal system is connected with the two sides of the grid-connected circuit breaker respectively. The data output port of the signal system is connected with the inverter. According to the invention, the technical problems in the prior art that by adopting the conventional grid connection mode of fans, the transient over-current is easily generated and the harmonic current of the non-periodic component is easily generated in the system-side current can be solved.