Objective To investigate the value of the magnetic resonance neurography three-dimensional sampling perfection with application optimized contrasts by using different flip angle evolution (3D-SPACE) in displaying the neoplasms of the lumbosacral plexus. Methods MRI 3D-SPACE images of 16 cases with neoplasm in the lumbosacral plexus collected during January 2018 to December 2023 were retrospectively analyzed. All cases were confirmed by pathology. The maximum diameter of the tumors was measured and the number of lesions was counted. The location of the involved lumbosacral plexus was observed and the number of the involved nerves was counted. The relationship between the tumors and nerves was evaluated. Results Ten cases were of single lesion and 6 cases were of multiple lesions. The average maximum diameter of tumors was （57.1±37.2）mm. Single nerve involved was detected in 5 cases while multiple nerves involved were in 11 cases. The relationship between the tumor and nerve was divided into three types. The tumor grew along the nerve in 5 cases. The nerves were compressed by the tumors in 5 cases, and were invaded and surrounded in 6 cases. Conclusions MRI 3D-SPACE can reveal the location and numbers of the tumor, displaying the relationship between the tumor and nerve clearly and intuitively, which is important for localization and diagnosis of the neoplastm in the lumbosacral plexus.