thank you,erikl! but i think what i meant was that i don't know exactly at which voltage the .measure statement will finish its measurement task, so i set the sweep rang of volt to be from 1v to 10v with an interval of 0.1v.when it sweeps to 4v(which i don't know beforehand),the .measure task accomplishes , so there is no need to sweep the voltage to 4.1v ,4.2v ,4.3v........in succession.so I need a control statement to stop the sweep simulation automatically when my measure statement has accomplished it measurement.