Chemical stability is considered a prior condition for the invariant magnetic properties under wide pH conditions for the recycling of TEPA-MP. In this paper, a series of experiments for the chemical stability of TEPA-MP under acidic and alkaline conditions were tested. The TEPA-MP particles were dispersed in different concentrations of hydrochloric acid (HCl) solution with pH values ranging from 0 to 3.0 for 12 h.