Objective To investigate the therapeutic effects of two parenteral nutrition (PN)methods in preterm infants. Methods Forty-two preterm infants who could not tolerate full enteral feeding were randomly divided into two groups. Twenty-two cases of the experimental group started to receive amino acids (AA) by 1.0 g/(kg·d) within 24 h after birth. Then AA was increased by 1.0 g/(kg·d)each day to maximum of 3.0 g/(kg·d)The dose and add method of intralipid was given alike AA within 48 h. Complete PN was achieved 5 d after birth. Twenty cases of the control group started to receive AA by 0. 5 g/(kg·d) ,and then increased by 0. 5 g/(kg·d) each day to maximum of 3.0 g/(kg ·d). The dose and add method of intralipid was given alike AA after 72 h. Complete PN was achieved at 8 or 9 d after birth. The feeding results was observed,the blood biochemistry was monitored at 72 h and 10 d after birth,and the incidence of complication was recorded. Results In comparison with the control group, time returning to birth weight, the weight loss rate, PN time and time returning to full enteral feeding were shorter in the experimental group (P ＜0. 01). There were no significant differences in the blood glucose,total bilirubin, urea nitrogen,carbon dioxide combining power,total cholesterol and the incidence of complication between the two groups (P ＞ 0. 05). Conclusion Quantity sufficient and early parenteral nutrition can be tolerated by preterm infants within 24 h after birth.