Why the <one-to-many> can't not specify a collum attrinute as the<manay-to-many> ? :((
Waht can I do in the situation that the parent table's primary collum name is different form the child's ?

Check the DTD and Docs but in anycase it is a sub node of the collection specification, eg, Notice the key node and column attibute.

<set
name="roles"
lazy="true"
inverse="true"
cascade="none"
sort="unsorted"
>
<key
column="principalKey"
/>
<one-to-many
class="persistent.domain.Role"
/>
</set>