Black phosphorus (BP) as a novel class of two-dimension (2D) materials has recently attracted large amount of attention as a result of its unique physical and chemical features. The remarkably strong light-matter interaction and tunable direct band-gap at a wide range make it an ideal candidate especially in the mid-infrared wavelength region as the saturable absorber (SA). Here the simple and effective liquid phase exfoliation (LPE) method was used to fabricate BP material and then a series of material characterizations (e.g., Raman spectrum measurement, TEM and AFM) were performed to exhibit its structure features. Using the balanced twin-detector measurement method, its saturable absorption property was comfirmed at 2 µm giving the modulation depth of 41.2% and saturation peak intensity of 3.767MW/cm2. By introducing this BP SA into two specifically designed fluoride fiber lasers both emitting around 3 µm, Q-switching with the pulse energy of 4.93 µJ and mode-locking with the pulse duration of 8.6 ps were obtained, respectively. The results suggest that BP is a class of promising and feasible material as the broadband SA for mid-infrared pulse generation.