The bulk polymerization and thermal properties of biodegradable poly(1,4-dioxan-2-one)[poly(p-dioxanone), PPDO] were investigated. The in vitro hydrolytic degradation behavior of PPDO monofilament sutures were also examined over a 16 week period at $37^{circ}C$ and $45^{circ}C$. The degree of PPDO polymerization decreased with increasing content of the initiator, lauryl alcohol[$CH_3(CH_2)_{11}OH$]. The thermal stability of PPDO was inversely proportional to the content of the catalyst, Sn(II) ethylhexanoate[$Sn(Oct)_2$]. Considering the efficiency of polymerization and the thermal stability of PPDO, the proper contents of Lauryl alcohol as an initiator and ethylhexanoate as a catalyst were 1600~1900 ppm and 20~30 ppm, respectively. Based on the determination of the half crystallization time, the crystallization speeds of dyed PPDO chip and monofilament suture were higher than those of undyed PPDO chip and monofilament suture. The maximum rates of crystallization of the dyed and undyed samples were observed at around $40{sim}50^{circ}C$ and $50{sim}60^{circ}C$, respectively. At the beginning of the in vitro time, the tensile strength of the PPDO monofilament suture decreased slowly but decreased considerably after a certain period, indicating that the degradation proceeded in two steps, the first occurring in the amorphous regions and the second in the crystalline regions. The average molecular weight of the PPDO monofilament suture decreased continuously from the beginning of the in vitro time, due to the random nature of the degradation process. The breaking strength retention (BSR) and molecular weight of the PPDO monofilament suture showed a quadratic function relationship.