N-nitrosamines have been detected in various water types. A strategy for removal of this group of compounds should be taken to reduce the health risks for humans. In this study, a fast and sensitive LC-MS/MS method was developed for quantitative analysis of nine N-nitrosamines and four precursors in a single sample. The Method Detection Limits (MDLs) in natural water ranged from 0.05 µg/L to 5 µg/L without using SPE pre-concentration. Three different types of activated carbon nanoparticles (NPs) (bamboo, charcoal and coconut shell as raw materials) were used to carry out removal experiments in two different pHs (pH 6.6 and 8.6). The results indicated that coconut shell-based activated carbon NPs had higher removal efficiency than the other two with a typical dosage of activated carbon NPs, at a typical contact time of 4 hours. No significant differences in removal efficiency between the two selected pH values were observed.