Abstract: Under the condition of solution culture, the effect of boron on the cell walll POD(peroxidase) activity and IAA(indole 3 acetic acid) oxydase activity of a typical B effecient and a B?ineffecient rape( brassica napus L.) cultivars were studied. The results showed that the activity of cell?wall POD significantly increased in root and significantly decreased in upper leaf of the two cultivars when B was removed from the solution at seedling, bolting and flowering stages. B starvation at the three stages had little effect on the cell?wall POD activity in lower leaf, but the activity of the emzyme in lower leaf was greatly higher in B?effecient cultivar than that in B?ineffecient cultivar. Under B deficient condition, the activity of cell?wall IAA oxydase significantly increased in root at bolting and flowering stages but increased at seedling stage insignificantly. The activity of the enzyme significantly decreased in upper leaf, except that at flowering stage, the enzyme activity changed insignificantly in B?effecient cultivar. B deficiency had no obvious effect on the enzyme activity in lower leaf, except that at flowering stage, the enzyme activity decreased significantly in the B?ineffecient cultivar.