Disclosed herein are an automated simultaneous separation system for radionuclides in multiple samples and a method for automatically separating uranium (U) using the same, which can automatically and simultaneously separate multiple samples. The automated simultaneous separation system includes: a solution distributor (30) for distributing a separation solution in seven directions; independent columns (80) of the same number as that of the samples, the columns (80) containing resin for chemical separation; a 8-channel tubing pump (60) for separately injecting the samples into the columns (80); first and second 3-way solenoid valves (50, 90) mounted at the front end and the rear end of the columns (80), and a digital pump speed controller (70) for freely controlling injection speed of the samples and solutions according to separation steps.