This invention relates to a device used to test the analyte in a liquid sample, including a test chamber (10) used to contain one or more test components, a collecting chamber (80) used to collect liquid sample, a piston chamber (100) between the test chamber (10) and the collecting chamber (80), a piston (200) and an opening (103). The piston (200) may move between two positions in the piston chamber, i.e., a first position and a second position. When the piston is in the first position, liquid can flow between a piston cavity (70) and the collecting chamber (80) through the opening (103)； during the piston's move from the first position to the second position, the opening (103) is sealed by the piston (200), wherein while the opening (103) is sealed by the piston (200), the liquid is released from the piston cavity (70) to the test chamber (10). This device can help to precisely quantify a liquid sample, with higher accuracy in the tests and higher comfort during the operations.
