The polymorphic and pseudopolymorphic forms of CG-400549, a novel FabI inhibitor with potent in vivo activity were prepared and characterized by differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TG). Seven crystal forms of CG-400549, one anhydrate and six solvates, have been isolated by recrystallization and the DSC and PXRD patterns of the seven crystal forms of CG-400549 were different respectively. The dissolution patterns of these seven crystal forms of CG-400549 were studied and they showed significant differences in the dissolution rate. After storage of 1 month at 0% RH (silica gel, $20^{circ}C$), 52% RH (saturated solution of $Na_2Cr_2O_7_{cdot}2H_2O/20^{circ}C$) and 95% RH (saturated solution of $Na_2HPO_4/20^{circ}C$), all crystal forms were not transformed.