From 15 October to 15 November 2017, two types of millimeter wave cloud radar (MMCR)(HT101, HMBKPS) installed on the “Science” marine science research ship were used for cloud observation in the West Pacific. Sounding balloons were released periodically during the observation; the accuracy of MMCR was analyzed according to the height of sounding out of cloud and into cloud. A visible light and thermal infrared dualband sky imager was also installed on the ship to obtain 24 h zenith image and MMCR data acquisition rate was analyzed by these images. The test results show that the data of two radars were highly consistent, the cloud base height correlation coefficient was 0.997, and cloud top height correlation coefficient was 0.988. The accuracy of cloud height observation by two types of MMCR was high; the average deviations of cloud base height between sounding and MMCR were 130 m (HT101) and 72 m (HMBKPS); the average deviations of cloud top height between sounding and MMCR were 310 m (HT101) and 190 m (HMBKPS), respectively. Affected by maritime climate and ship swaying, the cloud data acquisition rates of the two MMCR were 57.8% (HT101) and 68.7% (HMBKPS), respectively, and the missed clouds were mainly cirrus and cumulus clouds.