Spaceborne lidar is a promising tool for vertical ocean profile detection, which has attracted extensive attention in oceanic optical remote sensing technology. It is essential to evaluate the operating wavelength of spaceborne oceanic lidar to ensure that it is effective. In this paper, the optimal operating wavelength of spaceborne oceanic lidar for the purposes of global ocean detection was analyzed in terms of detection depth and signal-to-noise ratio (SNR). The global distribution of ocean detection depths and the corresponding wavelengths were estimated by using the oceanic optical properties data from MODIS. The SNR was evaluated based on the characteristics of the solar Fraunhofer line. It was found that ocean water with an optimal wavelength of 488 nm accounts for about 70% of the global ocean area and more than 95% of the global ocean area has a detected depth deeper than 0.8 times the depth of the euphotic layer. Furthermore, 70% of background light can be suppressed with a filter against the 0.1 nm bandwidth at the 486.134 nm solar Fraunhofer line and the SNR can be increased by about 5.0% compared to that of the 488 nm. In conclusion, working at 486.134 nm can effectively improve the detection depth and the SNR, so it is the optimal operating wavelength of spaceborne oceanic lidar.