Abstract: An all-automatic sieve instrument which makes use of a sonic viberation method to sieve the grain-like matter was designed. This instrument is characterized by its high analytical speed and high precision, esp. low sieving noise and low environmental pollution. It is suitable for the laboratory experiment, and can substitute for the triditional mechanical viberating sieve instrument. By using of microcomputer controlling the whole sieving process can eliminate the technician labour to a great extent. This instrument can be extensively apllie in the field of petroleum, geology, hgdroengineering, chemical industry, metallurgical industry, buiding material industry, medical indusry, light industry,energy industry etc.