The invention discloses an isothermal nucleic acid amplification reaction reagent which comprises Tris buffer solutions, potassium acetate, magnesium acetate, dithiothreitol, polyethylene glycol, adenosine triphosphate (ATP), deoxy-ribonucleoside triphosphate (dNTPs), phosphocreatine, creatine kinase, a primer group, single-strand binding (SSD) protein, colon bacillus helicase RecQ protein, UvsY protein and DNA polymerase. The invention further discloses an isothermal nucleic acid amplification method which includes steps of extracting DNA or performing inverse transcription after DNA extracting, and adding the isothermal nucleic acid amplification reaction reagent and reacting the mixture at a temperature in a range between 25 DEG C and 45 DEG C for 10 minutes to 60 minutes to complete the nucleic acid amplification. Compared with traditional polymerase chain reaction (PCR) technologies and according to the technology, nearly no professional instrument is needed, the operation is simple, technical requirements for operators are low, and the reaction time only needs about half an hour.