Objective：To compare the accuracy of three intraoral scanner-based complete arch implant impression techniques using TRIOS 3 and Aoralscan 3 intraoral scanners. Methods：A standard edentulous maxillary implant model with 6 screw-retained abutmentlevel scan bodies was constructed. The scan bodies were numbered from 1 to 6，from the right molar to the left molar area. A control group was generated by scanning the implant model using a desktop scanner. Three intraoral scanner-based scanning techniques were tested：without any scan aids，with scan aids but without calibration，and with scan aids and perform calibration. The tests were performed on 2 intraoral scanners：TRIOS 3 and Aoralscan 3. Each technique was repeated 10 times on each scanner. Scan bodies in the tested groups were superimposed onto the control group using scan bodies #1 and #2 as references to simulate the single-screw test. For each scan body，the distance between the centers of the screw-retained abutments in the test and control groups was measured to calculate trueness. The distance between the centers of the screw-retained abutments in each pair of scans within each test group was also measured to calculate precision. Trueness and precision of the 3 tested impression techniques were compared. Results：In both tested scanners，the trueness of the scanning group with scan aids（272.32 μm for TRIOS 3；240.00 μm for Aoralscan 3）was higher than that of the group without any scan aids（606.77 μm for TRIOS 3；413.78 μm for Aoralscan 3）（all P ＜ 0.05）. Furthermore，the calibration process further improved trueness（70.51% improvement for TRIOS 3；28.00 % improvement for Aoralscan 3）. For precision，the scanning group with scan aids（75.60 μm for TRIOS 3；69.91 μm for Aoralscan 3）and the group with calibration （74.36 μm for TRIOS 3；79.42 μm for Aoralscan 3）outperformed the group without any scan aids（487.75 μm for TRIOS 3；160.74 μm for Aoralscan 3）（all P ＜ 0.05）. However，there was no statistically significant difference between the scanning group with scan aids and the group with calibration（P ＞ 0.05）. Conclusion：The accuracy of intraoral scanning for full -arch implant impressions can be significantly improved by using scan aids combined with a calibration process.