A linear sliding rail has a self-lubricating unit capable of adjusting a lubricant amount supplied therefrom. The linear sliding rail has a sliding body and a lubricant tank fitted thereon. Within the lubricant tank, a lubricant-containing device is received, through which a lubricant is released to lubricant the sliding rail. Within the lubricant tank, there are also pressing bodies. Screws are used to assemble the components in the self-lubricating unit and penetrate and protrude the tank cover so that a distal end of each of the screws may be connected with an adjustment bolt. Thus, the purpose of lubricant amount adjustment may be achieved by placing the pressing bodies against the lubricant-containing device at different levels according to the user's requirement.