The invention relates to a dust prevention and water prevention structure of a fixing type nuclear radiation monitoring instrument. The dust prevention and water prevention structure of the fixing type nuclear radiation monitoring instrument solves the problems that a worker needs to use a steel structure frame in cooperation with a plastic pad, sealing glue and fastening screws to achieve expected dust prevention and water prevention effects for a prior fixing type nuclear radiation monitoring instrument, technology is complex, cost is high, and field maintenance of the prior fixing type nuclear radiation monitoring instrument is inconvenient. The dust prevention and water prevention structure of the fixing type nuclear radiation monitoring instrument is completed mainly by depending on a splicing structure composed of a plastic front panel and a plastic rear panel. A rubber pad, the sealing glue, the fastening screws and the like are not involved in the use process of the dust prevention and water prevention structure of the fixing type nuclear radiation monitoring instrument. Furthermore, the dust prevention and water prevention structure of the fixing type nuclear radiation monitoring instrument can achieve an IP54 protection effect, and is low in weight, simple in process, low in cost, high in reliability, and suitable for field maintenance of the instrument.