The utility model provides an on - -spot suction filter device of seawater sampling constitutes characterized in that by bottle plug, filtration tray, bottle, sampling pipe: be equipped with sampling pipe joint, sealing washer on the bottle plug, filter the tray lower edge and be equipped with joint strip, the glass psammitolite piece of keeping flat in the filtration tray, the filter membrane of keeping flat on the glass psammitolite piece, the bottle plug passes through fixed buckle of bottle plug and bottle sealing connection to compress tightly the filtration tray, make bottle plug and bottle sealed air tight through sealing washer and joint strip, be equipped with the interface of bleeding on the bottle, the fixed buckle of the switch that turns on the water, containing mark, bottle plug, the sampling pipe is equipped with degree of depth scale, and its upper end links to each other with the sampling pipe joint of bottle plug, and the lower extreme is equipped with the unilateral control valve and the unilateral control valve is acted as go -between. Simple structure, convenient to use, flexibility, the wide application is sampled in different degree of depth water layers, has that the sampling is accurate, the sample is pollution -free, characteristics of suction filtration high efficiency, labour saving and time saving, operation safety.