Objective: To investigate the rule of the alignment of the major and minor segments of the maxillary alvedar bone in infants with comp lete unilateral cleft palate (CUCP).Methods: 30 models of CUCP were used in the study,Markers on the model were designed.The lenth,width, midline and the malposition of minor and major segments on both sides of the cle ft were measured and analyzed.The models of 9 normal infants were employed as th e controls.Results: In CUCP group,the width of alvelar arc h was found significantly larger ( P