The type of development of Heilu soil are related to nonexchangeble potassium in Heilu soil of loess region.The present paper deals with prelimiary study on the genetic characteristics and nonexchangeable potassiumof profle in major soil types of Heilu soil.The results obtained are summarized as follows:The distribution of nonexchangeable potassium on soil profile in lisht-textured soil

ortho Heilu soil and resty Heilu soil accord with expaonental equation.It is one principle feature in Heilu soil of stepperegion.The distribution of nonexchangeable potassium on profile of argillic Heilu soil is "S"formed.It is the transitional form of forest-steppe region soil from the lou soil of forest region to light textured soil or the Heilu soil rusty Heilu soil of steppe region

The form of them has some features of the distribution as nonexchangeable potassium in the lou soil profile

but the contents are different.The distribution of nonexchangeable potassium on the profile are same of on the Heilu soil of the forest-steppe region in the gully land

gully plain land and river platform of the stppe region.