Four ionic liquids (ILs) were synthesized by a simple neutralization reaction using 1,8-diazabicyclo[5.4.0]undecane-7-ene as the cation and organophosphonic acids with different carbon chain lengths as the anion. The obtained ILs had an excellent water soluble property and the tribological performance was studied by a four-ball friction tester. The results showed that the longer carbon chains, the better tribological properties of the ILs. Compared with the blank, only 0.05 wt% of ILs addition resulted in the decrease of friction coefficient and wear volume about 30% and 60%, respectively. The adsorption state of the ionic liquid on the steel surface was also investigated by molecular dynamics simulation. It is believed that the good tribological performance and corrosion inhibition was attributed to the effective physical adsorption due to the polarity of the organophosphonate, which can form an effective adsorption film and prevent the steel surface from corrosion.