High-energy electrons escaped from pulsar wind nebula (PWN) could produce synchrotron X-ray emissions through interactions with the interstellar magnetic field, resulting in the formation of an X-ray halo around middle-aged pulsar. We study the prospect of detecting X-ray halos with eROSITA from ten X-ray halo candidate pulsars. We find that most of the X-ray halos are found to be bright enough to be detected by eROSITA with a 20 ks targeted survey. Among these pulsar halos, four are detectable in the 4-yr all-sky survey. We show that eROSITA is expected to be able to constrain the magnetic field and diffusion coefficient in the pulsar halos.