Abstract: As human space activities expand to the Moon, Mars, and deeper and beyond, the current time rules charac-terized by timekeeping-timedisseminating are no longer applicable beyond the Earth.How to unify the time beyond the Earth?This has become a major scientific problem in physics, astronomy, space science and metrology.This paper analyzes that the rule of time on the Earth is limited by geoid conditions, and that time service or time dissemination techniques are not suitable for spanning different coordinate systems or where the effects of relativistic could not be ignored.The relative time view is proposed, comparing the difference with the absolute time view from 6 aspects of standard time, the method to unify time, the method to treat relativistic effect, time uniformity, and the time index for calendar, and understanding of simultaneity.A new time-keeping system based on the proper time and coordinate time of general relativity is proposed.The five differences between the existing time rules and the space time-keeping system are compared.The space timekeeping system could become one of the way to deal with the problem to unifiy time beyond the Earth.