>While i coding as below : REPORT FORM INV_FORM TO INV_RPT
>That will create a file name : INV_RPT
>I want to know how can i print the document from INV_RPT.

One way is to

COPY FILE inv_rpt TO LPT1 &&or some other printer connection than LPT1

Using the REPORT FORM syntax this way (printing to file first, then sending file to printer) is usually only needed on a machine that has no printer readily available. If you do have a printer readily available, you can use

REPORT FORM INV_FORM TO PRINT

HTH