A low-field ,1,H quantitative nuclear magnetic resonance（LF－,1,H qNMR） spectroscopy was developed for the simultaneous quantification of ketamine and 4 adulterants，i.e. dimethyl sulfone，sulfanilamide，niacinamide，and phenacetin in this paper．Meanwhile，its quantification ability was compared with that of high-field ,1,H quantitative nuclear magnetic resonance（HF－,1,H qNMR）．As for LF－,1,H qNMR，the intra-day relative standard deviations（RSDs），inter-day RSDs，and limit of quantitations（LOQs） for ketamine and 4 adulterants were in the range of 0.50%－2.9%，2.0%－7.4% and 0.3－5 mg/mL，respectively，while for HF－,1,H qNMR，the intra-day RSDs，inter-day RSDs and LOQs were 0.40%－1.1%，1.5%－3.9% and 0.003－0.05 mg/mL，respectively．Both LF－,1,H qNMR and HF－,1,H qNMR were applied to the quantification of 167 seized ketamine samples．The quantitative relative errors of LF－,1,H qNMR and HF-,1,H qNMR for ketamine and adulterants were all lower than 15%．The purity ranges of ketamine，dimethyl sulfone，sulfanilamide，niacinamide，and phenacetin determined by LF－,1,H qNMR were 13.5%－102.6%，1.1%－81.3%，2.6%－83.4%，1.8%－22.7% and 3.4%－43.8%，respectively，while those of ketamine，dimethyl sulfone，sulfanilamide，niacinamide and phenacetin determined by HF－,1,H qNMR were 13.2%－99.7%，1.0%－78.4%，2.5%－75.9%，1.7%－21.3% and 3.0%－43.5%，respectively．Both LF－,1,H qNMR and HF-,1,H qNMR could realize the simultaneous quantitative analysis of ketamine and the adulterants without using reference materials．Although the precision and sensitivity of LF－,1,H qNMR are slightly lower than those of HF－,1,H qNMR，its simultaneous quantification ability toward multi-components in complex matrices is exciting．LF－,1,H qNMR will be more widely used in forensic science laboratories in the future due to its low costs in instrument purchase and daily maintenance.