We carried out high-precision photometric observations of three eclipsing ultrashort-period contact binaries (USPCBs). Theoretical models were fitted to the light-curves by means of the Wilson-Devinney code. The solutions suggest that the three targets have evolved to a contact phase. The photometric results are as follows: a) 1SWASP J030749.87−365201.7, q = 0.439 ± 0.003, f = 0.0±3.6 %; b) 1SWASP J213252.93−441822.6, q = 0.560±0.003, f = 14.2±1.9 %; c) 1SWASP J200059.78+054408.9, q = 0.436 ± 0.008, f = 58.4 ± 1.8 %. The light curves show O'Connell effects, which can be modeled by assumed cool spots. The cool spots models are strongly supported by the night-tonight variations in the I-band light curves of 1SWASP J030749.87−365201.7. For a comparative study, we collected the whole set of 28 well-studied USPCBs with P < 0.24 day. Thus, we found that most of them (17 of 28) are in shallow contact (i.e. fill-out factors f < 20 %). Only 4 USPCBs have deep fill-out factors (i.e. f > 50 %). Generally, contact binaries with deep fill-out factors are going to merge, but it