I am facing some problems in making and flying RC glider such as
I had checked my Glider's CG many time which was in 1/3 of chord of wing, checked the imbalancing weight and tuned turning surfaces straight ,then also my glider is turning automatically. what to do?

Some pics would really help , helping you mate.

sorry for the delay
my plane body is simple made out of corrugated sheet and wing material is also same. total weight of plane is about 700g.

Do you mean a turn(yaw) or roll?

yaw.

is it turning left or right.....?

plz post few more pics of the motor mounting....

There are also other factors  responsible .... considering everything in design is right then
How big is your propeller?
If its more than 5 inch,have you given down right offset to motor?

Your wing width is shorter than normal but that is not a very big issue.  Fyi,  wingspan/6 or wingspan/7 should be the width of a rectangular wing with or without dihedral.
The turning effect is probably  due to:
1) your vertical stabilizer is not straight or your vertical stabilizer is not perpendicular to the plane,  even 5 degrees can make a huge difference.
2) your vertical stabilizer's shape is not right( for example,  the left side curve is not equal to right side curve). The full shape should be a hydrodynamic shape when seen from the top.
3) your main wings are not parallel to the plane.  As I said above even 5 degrees make a huge difference.
4) your main wings aren't made right.  The aerofoil should be equal at all places and a little crest or trough affects aerodynamic performance acutely.  Did you cut it yourself or used a hot wire cutter?  The uneven surface of the aerofoil produce different lifts at different places causing one part to lift up thus causing a yaw overall.
5) this should be the main reason for your yaw,  your motor isn't placed right.  If you use a propeller of size less than 7 inches,  you should make the motor mount perpendicular to the plane.  If the props are like 10 inches or such,  then put two washers in the screws connecting the motor and the motor mount. That is,  if the plane is going left,  put the washers on the two screws in the left ( if you are using the x screw configuration then put a washer on the left screw).  If the plane is going right,  put the washers in the screws of the same side. 
P. S: Sorry for a very large reply as I wanted to tell all the factors affecting the yaw of a plane.
Regards