To accurately transfer the leveling data at a long distance under complex sea environment and conditions, a portable long-distance illuminating beacon lamp is designed using the total station trigonometric leveling method for long-distance cross-sea elevation transfer. The light width and brightness of the beacon can be adjusted as per the length of observation route and atmospheric environment to meet the night observation requirements under different route lengths; it is simple in structure, small in size, and light in weight. Moreover, the dispersion of target and observation data in long-distance illumination is avoided. With the help of data acquisition software, the automatic verification of observation data is realized, and the surveying efficiency is considerably improved. The beacon with a measuring distance of 5.5 km was applied for the ShenzhenZhongshan link, and the applicable results meet the accuracy requirement of second-class cross-sea level survey, which indicates the feasibility of the beacon in precise long-distance cross-sea elevation transfer.