The present invention relates to a method for producing an antimicrobial polyester fiber yarn containing volcanic ash, the method comprising the steps of: crushing and heating volcanic ash, and allowing the heated volcanic ash to collide under an air stream in an air classifier mill system to obtain volcanic ash powder； subjecting the volcanic ash powder to nano-milling to obtain nano-sized volcanic ash particles； disintegrating the volcanic ash particles to prepare nano volcanic ash； mixing the prepared nano volcanic ash with polyester for fiber use at a weight ratio of 10:90-30:70, followed by melt extrusion, thereby preparing a highly dispersed volcanic ash master batch； and mixing the volcanic ash master batch with polyester for fiber use at a weight ratio of 4:96-8:92, followed by spinning to produce an antimicrobial polyester fiber yarn.
