This study investigated the effects of cinnamaldehyde on putrescine production by Obesumbacterium proteus in pure cultures and Xinjiang sausage. Scanning electron microscopy was used to analyze the cell morphology of the test bacteria, and reverse transcription real-time fluorescence quantitative polymerase chain reaction was employed to analyze the gene expression of arginine decarboxylase and ornithine decarboxylase of the test bacteria at different cinnamaldehyde concentrations. Single-molecule real-time sequencing was utilized to identify the species composition of the sausage. Moreover, relevant parameters such as putrescine accumulation and microbial growth were evaluated. The results indicated that cinnamaldehyde inhibited the growth of O. proteus by leaking its contents and changing membrane permeability, and significantly reducing putrescine accumulation by inhibiting the expression of arginine decarboxylase (adiA) and ornithine decarboxylase (speF) genes. The cinnamaldehyde concentration revealed an inverse relationship between gene expression and putrescine accumulation. Besides, cinnamaldehyde significantly reduced the abundance of harmful bacteria (Enterobacteriaceae and Pseudomonas), alleviate putrescine content and stimulate the release of amino acids in the sausage. Therefore, adding cinnamaldehyde is an effective method to inhibit putrescine accumulation and reduce the growth of spoilage microorganisms in the sausage.