I have got the Solution of this issue. change the field_array parameter value.
now it return date in a array name date. If I change it two sdate for start date and edate for end date it will solve the issue.
{html_select_date start_year=1970 month_format="%b" field_order="dmy" field_array="sdate" prefix="" day_id="edd" class='sd_class' month_id="edm" year_id="edy" year_empty="Year" month_empty="Month" day_empty="Day" time=$edate }