To better apply fiber-reinforced concrete in 3D printing construction, this paper investigates the optimal dosage of basalt fiber (BF) in 3D printed concrete(3DPC) and optimizes the printing parameters through experimental studies. Firstly, the effects of different dosages of BF on the flowability, mechanical properties, and extrudability of concrete were systematically analyzed to determine the optimal fiber content. Secondly, based on a cylindrical construction model with a centerline diameter of 200 mm, printing was conducted using the optimal mix ratio. The influence of three key process parameters (layer height, extrusion rate, and horizontal movement speed) on the printing morphology was studied, and their mechanisms and failure modes were analyzed, ultimately obtaining optimized printing parameter configurations. The results indicate that as the BF dosage increases, the flowability and extrudability of concrete decrease, while the compressive and flexural strengths were significantly enhanced. The comprehensive performance of the material reaches its optimum when the BF dosage is 0.3%. Additionally, when using a 20 mm circular nozzle for printing, the optimal parameters for layer height, extrusion rate, and horizontal movement speed are 8 mm, 0.5 rad/s, and 30–50 mm/s, respectively. The research results provide theoretical foundations and technical support for the application of fiber-reinforced concrete in 3D printing construction.