This study was purposed to investigate the practicality of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) for detection of single nucleotide polymorphisms (SNP) on jak2 gene in multiple myeloma (MM) cells. The DNA fragment containing 2 SNPs of jak2 (C428T and C643T) was amplified using PCR and was purified. The purified product was used as the template for primer extension (PEX). The small products of allele-specific reaction were purified, the SNPs on jak2 gene of 5 patients with MM and 5 healthy persons were detected by MALDI-TOF MS. The results showed that the distribution of genotype C428T and C643T was not different between MM patients and healthy persons, both of which are homozygous T/T. In conclusion, the method based on MALDI-TOF MS and PEX technique for detecting SNP in jak2 gene is rapid, accurate and reliable method, and can be used in clinical practice.