Device and method for measuring viscosity and density of fluid

The invention belongs to the field of fluid viscosity and density testing, and discloses a device for measuring viscosity and density of a fluid. The device comprises a first cavity, a second cavity, a third cavity, a first pipeline, a second pipeline, a third pipeline and a fourth pipeline. The first cavity is connected with the second cavity through the first pipeline, and a vibrating tube densimeter and a viscometer are arranged on the first pipeline; the two ends of the vibrating tube densimeter are connected with phase-locked amplifiers; one end of the third pipeline is connected with the third cavity, and the other end is connected with one ends of the second pipeline and the fourth pipeline; the other end of the second pipeline is connected with the first pipeline; the other end of the fourth pipeline is connected with the first cavity; the first cavity, the second cavity and the third cavity are all connected with a driving device; and a first pressure sensor is arranged at one end of the viscometer,