A facile approach was developed to produce MoS2 nanosheets by ultrasound-assisted reflux exfoliation, which was highly efficient for large-scale production and sustainable for environment. The interlayer force of bulk MoS2 was first exhausted in employing LiOH/NaOH solution by reflux and thereafter quickly exfoliated by ultrasound. The lateral size of the as-prepared MoS2 nanosheets with about 2-9 layers became smaller. Definitely, the average friction coefficient and wear scar diameter of 0.08 wt % MoS2-based oil decreased by about 21.87 and 38.09% relative to the base oil, which displayed better antifriction and antiwear performances.