A total of 118 juvenile Toad-headed Lizards (Phrynocephalus frontalis) were collected in September 2011 from Kubuqi desert (40°12′N,111°06′E), Inner Mongolia. We measured snout-vent length, head width, tail length and abdomen length to analyze their sexual dimorphism. by t-test and regression analysis. The male was significant larger than the female in snout-vent length (SVL) (t=3.702, df=116, P<0.001). The mean SVL of males was 36.3mm while the mean SVL of females was 34.0mm. The male had a bigger head (t=4.616, df=116, P=0.002) and longer tail (t=3.958, df=116, P<0.001), while the female had bigger abdomen (t=2.292, df=116, P=0.024). All the morphological traits measured were positively related to SVL.