Abstract: Two large-diameter single-bounce ellipsoidal capillary lens were designed for synchrotron radiation source, one was coated and the other was not．Performance was simulated with a surface error model．Entrance diameter of Ir-coated capillary was 19.0 mm, focal spot size was 7.1 μm, focal depth was 0.2 mm; receiving solid angle was 3-fold of uncoated one．Entrance diameter of uncoated capillary was 15.0 mm, focal spot size was 6.4 μm; focal depth was 4-fold of Ir-coated one．The relationship between surface error and focal spot size was studied．The application of large-diameter single-bounce ellipsoidal capillary in related X-ray technology was discussed．