The invention discloses a surface tension measuring device and measuring method for a droplet on a vertical plate. The device comprises a light source, a glass plate, a linear array CCD and a computer, the light source is used for generating a horizontal light beam, the glass plate is arranged on an optical path as the vertical plate, a to-be-measured droplet is arranged on the surface of one side, close to the light source, of the glass plate, the to-be-measured droplet is penetrated by the light beam, the linear array CCD and the light source are respectively arranged at two sides of the glass plate, the linear array CCD and the light source are arranged in a corresponding manner, and the diffraction light intensity distribution after transmission of the to-be-measured droplet by the light beam is acquired through the linear array CCD and transmitted to the computer. According to the device and method, the to-be-measured droplet is arranged on the vertical glass plate, diffraction signals of the light beam are acquired and analyzed so that a liquid surface tension coefficient is obtained, a to-be-measured sample is only the droplet, the sampling of the to-be-measured droplet is small, the equipment is simple, and the operation is convenient.