Particle confinement with current ramp is investigated in the HL-IM tokamak. The ratio of particle confinement time to energy confinement time is used to determine confinement improvement. It increases a factor of 3 after the current rises twofold. An optimization density range to improve particle confinement is (1.5-3.5) XlO19 m-3. Particle confinement improvement during current ramp-up is beneficial to the startup of fusion reactors.