Iodonium salt initiator and processing-free thermally sensitive plate precursor containing thereof, and processing-free thermally sensitive plate and use thereof, At least one of two para positions of two benzene rings of the iodonium salt initiator is an alkene group containing a carbon or nitrogen or oxygen atom and a double bond at an end. The alkene group can increase a steric hindrance of the iodonium salt, improves compatibility of the iodonium salt, the thermosensitive resin and the crosslinkable prepolymer, reduces the surface migration of the iodonium salt in the imaging layer and improves the initiation efficiency. During the laser imaging, a double bond contained in a residual end of the iodonium salt can perform a crosslinking reaction with the thermosensitive resin and the crosslinkable prepolymer, and thus reduces damage to the imaging layer caused by small molecules. At the same time, substituents can be arranged at four meta positions of the two benzene rings to increase the steric hindrance of the iodonium salt, and therefore, the surface migration of the iodonium salt in the imaging layer is further reduced, and the initiation efficiency is improved and the performance of the processing-free thermally sensitive plate is further improved.