Acetic acid is the main component of acids generated through oil-paper insulation aging. The analysis of the content of acetic acid dissolved in the transformer oil is of great significance for evaluating the aging state of operating transformer. Raman spectroscopy is a molecular analysis technology based on the Raman effect, which can be applied to perform non-contact in-situ detection of substance. In this paper, the application of laser Raman spectroscopy in the detection of acetic acid dissolved in the transformer oil was studied. Gaussian 09W simulation software was applied to analyze the Raman vibration characteristics of acetic acid. Also, the vibration modes of the Raman spectral peaks of acetic acid were identified. Acetic acids at different concentrations dissolved in the transformer oil were directly detected based on the laser Raman spectroscopy liquid detection platform. Acetic acid was characterized by Raman signal at 891 cm-1. The quantitative analysis method for acetic acid was established based on the Raman peak area ratio, A891 cm-1/A932 cm-1, and the least squares method. Current detection limits of 0.08 mg·mL-1 acetic acid concentration were obtained. The experimental results show that laser Raman spectroscopy can be used in the analysis of the content of acetic acid dissolved in the transformer oil which has a good detection stability and reproducibility. The research in this paper provides a new alternative method for the rapid and nondestructive detection of acetic acid dissolved in the transformer oil.