The in-situ testing based on the seabed drill rig is a new way to place sensors into the earth. Combined with the actual working condition of seabed drill rig, a set of multi-function in-situ tester based on cone penetration testing(CPT) was developed, which was able to capture tip-resistance, sleeve-friction, pore-pressure, temperature, electrical-resistivity and video under 2 000 m water. The test method, system architecture, cone and test sensors, and data acquisition were described in detail. The field test confirmed that the in-situ tester work properly in accordance with a predetermined design, and the test data is consistent with the data of seabed CPT system.