The invention relates to a method for testing the particle size and the particle size distribution of 5-aminotetrazole, wherein the particle size and the particle size distribution of an organic synthesis intermediate 5-aminotetrazole are tested by a wet laser diffraction method. According to the method, 5-AT particle size test is performed by using a trichloromethane solution containing 0.2-0.4%of sodium dodecylbenzenesulfonate and 0.1-0.2% of ethylphenyl polyethylene glycol as a dispersion system at an ultrasonic dispersion time of 5-10 min. According to the present invention, the relativestandard deviation of the multiple median particle size measurement results is not more than 6%, the precision of the method is good, and the wet laser diffraction method for testing the particle sizeof 5-AT has good applicability and can be used for the test of the particle size of 5-AT so as to be used for the quality control of the product.