Shipboard Meteorological Instrument is used in meteorological observation at sea and sailing.The comparative test on the sea between two Shipboard Meteorological Instruments is introduced in this paper.The result indicated that the instruments had high internal consistency reliability in atmospheric temperature relative humidity and atmospheric pressure.The correlation results of different instruments are more than 0.9.Though there were some differences between the data of wind speeds for the actual environmental conditions, they had high internal consistency reliability in tendency chart.The differences of wind direction were small when they were converted. As a whole, the performance and stability of Shipboard Meteorological Instrument are stable.