The crystallization behavior and intriguing crystal morphologies of double crystalline poly(p-dioxanone)-poly(tetramethylene ether)glycol (PPDOPTMEG) multiblock co-polymers were investigated via differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and transmission electron microscopy (TEM). The effects of composition and microphase morphology on the crystallization of each segment were also explored. The results indicated that PPDO segments and PTMEG segments were immiscible. Composition and unique microphase morphology affected the crystallization ability and crystal morphology of PPDO and PTMEG segments. The kinetics of isothermal crystallization was studied calorimetrically and microscopically. It was found that crystallization rate of PPDO segment was slower than that of PPDO-H, which should be responsible for the dilution of PTMEG segments. In the case of PTMEG segments, the crystallization kinetics were highly correlated with the microphase morphology.