The statistics result finds that the net export only in the first appreciation scan after 23 months excels the level before RMB depreciation in four depreciation scans in the exchange of Renminbi to Japanese Yen from January, 1993 to December, 2010, while the net export is no more than the level of predepreciation time in the other three scans, as a result, the tradition Jcurve does not exist. Calculation analysis shows that the longrun depreciation of Renminbi to Japanese Yen causes the decrease of the ratio of export to import because import is more than export, that shortterm exchange rate depreciation leads to the decrease of the proportion of export to import and that the rate of export to import rises after 3 quarters.