解决方案是在构造函数中指定“ lineterminator”参数:
file = open('P:\test.csv', 'w')
fields = ('ItemID', 'Factor', 'FixedAmount')
wr = csv.DictWriter(file, fieldnames=fields, lineterminator = '\n')
wr.writeheader()
wr.writerow({'ItemID':1, 'Factor': 2, 'FixedAmount':3})
file.close()