The effects of recess length in a liquid-centered swirl coaxial injector on the spray characteristics have been investigated using a Dantec phase Doppler anemometry (PDA) system and a Photron Fastcam SA-1.1 camera. The spray cone angle and droplet Sauter mean diameter (SMD) were characterized at predefined recess lengths and pressure drops. It is found that recess is the key geometrical parameter to excite self-pulsation for the given gas and liquid mass flow rates. Once the recess length approaches or exceeds a critical value which is related with the spray cone angle of liquid pressure swirl injector, self-pulsation is excited, and the spray cone angle increases significantly. With further increase of recess length, the spray cone angle of both stable spray and self-pulsated spray decreases gradually. The drop size and its distribution are heavily influenced by both recess length and gas-to-liquid mass ratio (GLR). When the GLR is relatively low, with the increase of recess length, the global Sauter mean diameter (GSMD) of the spray increases gradually and SMD distribution varies from a 'Lambda' shape to a hollow cone shape. However, when the GLR is large enough, with the increase of recess length, the GSMD increases slightly at the beginning of self-pulsation and then decreases gradually, and the distribution of SMD shows a slant 'N' shape for both stable and self-pulsated sprays. Independent of recess length, the GSMD of the spray decreases with GLR.