Pretreatment system for water sample

The invention provides a pretreatment system for a water sample. The pretreatment system comprises a sample introduction unit, a primary liquid storage unit, a secondary liquid storage unit, enrichingunits and a nitrogen blowing concentrating unit, wherein the sample introduction unit comprises a funnel and a water conveying pipe which are connected with each other, and a filter is arranged in the water conveying pipe; the water conveying pipe is connected with the primary liquid storage unit; the secondary liquid storage unit comprises three or more liquid storage devices, the enriching units comprise three or more enriching columns, the liquid storage devices and the enriching columns are connected in a one-to-one correspondence manner through pipelines and valves, filter membranes arearranged at inlets of the liquid storage devices, and the inlets of the liquid storage devices are connected with the primary liquid storage unit through pipelines and valves; the enriching columns are connected with the nitro