The invention discloses a hydrogen isotope crystallization height and surface roughness interference measurement device and method, and the device comprises an interference measurement system, a displacement system, and a computer processing module. The method comprises the following steps: in a microscopic observation mode, controlling a displacement system to scan and shoot a whole crystal growth surface, performing image splicing to obtain images of all regions, and determining an accurate position needing to be monitored; and aligning the observation field of view of the measurement systemwith a monitoring area, switching to an interference measurement mode, and realizing measurement of the growth height and the final growth state surface roughness of the area to be measured by usingan interferogram fringe phase measurement technology. By utilizing the device and the method provided by the invention, the non-contact measurement of the growth height and the surface roughness of the hydrogen isotope low-temperature crystal can be realized, the influence of vacuum chamber glass, strong reflection light of a growth substrate, boundary fracture in the growth process and the like on a common interference microscopic system is eliminated, and high-precision measurement is realized.