Objective  To compare the myopic anterior corneal surface measurements of the Q value and corneal power provided by Pentacam， iTrace and Orbscan Ⅱz and evaluate the agreement among the 3 methods. Methods  This was a cross-sectional study. One hundred eyes were chosen from 100 myopic patients and the Q value and mean Sim K of the anterior corneal surface was measured by Pentacam， iTrace and Orbscan Ⅱz in the same patient′s eye. Measurement results were compared using analysis of variance and agreement among the measurements was assessed using Bland-Altman plots. Results  The Q value measurements were -0.09±0.12， -0.09±0.09， and -0.18±0.10 with Pentacam， iTrace and Orbscan Ⅱz， respectively. The Q value measurements with Orbscan Ⅱz were lower than those with Pentacam and iTrace （F=43.06， P<0.01）. For the Q value measurements， the 95% limits of agreement （LoA） was small between iTrace and Orbscan Ⅱz （from -0.08 to 0.26） and the 95% LoA was large between iTrace and Pentacam （from -0.23 to 0.23）. The respective mean Sim K measurements were 43.34±1.37 D， 43.30±1.35 D and 43.56±1.36 D with Pentacam， iTrace and Orbscan Ⅱz. The mean Sim K measurements with Orbscan Ⅱz were greater than that with Pentacam and iTrace （F=23.25， P<0.01）. For the mean Sim K measurements， the 95% LoA was small between iTrace and Pentacam （from -0.68 to 0.59 D） and the 95% LoA was large between iTrace and Orbscan Ⅱz （from -1.15 D to 0.63 D）. Conclusion  Measurements of Q value and mean Sim K of the anterior corneal surface of myopes showed statistically significant differences among the 3 instruments. The agreement among the 3 instruments was not comparable for Q value measurements. The agreement between iTrace and Pentacam had comparable results for mean Sim K， and can refer to one another.