Seawater measurement unit

The invention discloses a seawater measurement unit, comprising outer and inner barrels each having a bottom opening, and a plurality of measuring probes; the top inner side of the outer barrel is provided with sponge, a center push rod is passed through the top of the outer barrel, the sponge and the top of the inner barrel, the upper diameter of the center push rod is greater than its lower middle diameter, the top end of the center push rod is connected with an external electric push rod, the bottom face of the upper portion of the center push rod is abutted to the top outer side of the inner barrel, and the bottom end of the center push rod is connected with a seal; in the first phase where the seal contacts the inner peripheral wall of the inner barrel, the inner barrel is removed from seawater level, and seawater is discharged; in the second phase where the seal contacts the inner peripheral wall of the inner barrel, a cylindrical inner cavity of the inner barrel is sealed, a plurality of equal height s