Considering that the signal analysis is usually based on dual-way intensity detection, a novel method is demonstrated that uses Stokes vector method to analyze the degree of polarization degree in the optical fiber current sensor. In approximate conditions, the reduction transmission matrix is deduced and obtained of the full optical fiber current sensor based on Mueller matrix. It is found that the effect of the Stokes vector method is similar to the Jones vector method; by comparing the Jones vector method with the actual experimental results, it is easy to know that the Stokes vector has more operational advantages, such as only real numbers included in the Mueller matrix, easily being changed to sparse matrix and the final polarization degree being obtained by calculating the second diagonal element of the total transmission matrix. This method can be used in the theoretical analysis of the degree of polarization, and simplify the analysis process and operation process effectively.