The invention provides a liquid-solid separation process for suspending liquid, which is suitable for a situation that the solid content in the suspending liquid to be separated is less than or equal to 100g/L. The structure of a liquid-solid separation system for the suspending liquid is as follows: slurry after desilication in a suspending liquid tank is delivered to a high-efficiency filter through a feed valve, and the high-efficiency filter delivers filtered turbid solution back to the suspending liquid tank through a circulating valve; the high-efficiency filter delivers filtered clear solution to a clear solution tank through a discharge valve; and solid filter residue and attached liquid thereof after the filtration of the high-efficiency filter pass through a residue discharging valve on the lower part of the high-efficiency filter and enter a filter residue storage tank. The process greatly simplifies flow, reduces construction investment, improves labor productivity and reduces production cost.