Fusarium rot of muskmelon fruit is a common postharvest disease, which not only causes quantity deterioration but also leads to trichothecene accumulation in decay fruits. Neosolaniol (NEO) is one of main trichothecene, which poses a severe threat to human health. In this study, UPLC-MS/MS method was developed to determine NEO in muskmelon inoculated with Fusarium sulphureum. Diatomite was used to remove NEO in muskmelon and the adsorption kinetics, adsorption thermodynamics were analyzed in this adsorption process, and the changes of muskmelon juice quality before and after adsorption were investigated. The results showed that diatomite was a good adsorbent to remove NEO from muskmelon juice. The reaction process fits the Langmuirmodel and it was spontaneous exothermic reaction and not easy to be desorbed; the kinetic results showed that the maximum adsorption capacity was 12.35 mu g/g, and this process fits the Pseudo-second-order model; diatomite had no significant effect on juice quality.