Using a new method of multi-frequency of K parameter, we estimate the ratio
of altitudes of radio emission region of pulsars at 430 and 1418 MHz. The
value of the ratio is 1.34+/-0.12 and the power law index of altitude-frequ
ency is 0.24+/-0.08. It is indicated that the lower radio frequencies origi
nate further out and the emission region is radially narrow.