I want a border(like a frame) around my xsl-region-body on every page of my document.

Some FO processors support border properties for the region
FOs:
  <fo:region-body border="1pt solid black".../>
however, the spec explicitely forbid this.
Other approaches are using overlapping regions with a properly
blaced block-container:
 <fo:simple-page-master height="22cm" width="12cm"
   margin-top="1cm" margin-left="1cm" margin-right="1cm"
   margin-bottom="1cm" ... >
   <fo:region-body margin-top="1cm" margin-bottom="1cm" ... />
   <fo:region-start extennt="10cm"/>
 ....

  <fo:static-content flow="xsl-region-start">
    <fo:block-container top="0" left="0" width="10cm"
      height="20cm" border="1pt solid black">
      <fo:block>&#160;</fo:block>
     </fo:block-container>
    ...
or using an appropriate image as background for the body region.