Аннотация:An algorithm is developed for reconstructing the angular diameter of a star, based on an analysis of the diffraction pattern observed during lunar occultation of 61 Delta-1 Tauri. The observations were carried out with the 48-cm reflector of the High Mountain Tian' Shan Expedition of the Shternberg State Astronomical Institute in Alma-Ata, USSR. The angular diameter obtained with the algorithm was 0.0028 (+ or 0.0007) arcsec. On the basis of the diameter calculation, the linear radius of 61 Delta-1 Tauri was estimated to be about 14 solar radii and its effective temperature was 4700 K. The estimate of effective temperature is found to agree with the KO III CN 0.5 spectral class.