An analysis of splice loss between photonic crystal fibers (PCFs) and conventional single-mode fibers (SMFs) is presented at bending and straight conditions, by using scalar effective index method (SEIM), vectorial effective index method (VEIM), and finite-difference frequency domain (FDFD) methods. It is shown that when there is a slight bending at the vicinity of splice joint, the spot size increases sharply at higher frequencies. On the basis of the obtained results, a mechanism to optimize the splice loss between PCFs and conventional SMFs, both with any geometry, is suggested. The results can be utilized for PCF-based devices to be jointed to SMF as a transmission medium.