Hi , Is there any way to test the positioning and repeated positioning accuracy of the CNC.?
Thanks 
Do you have a dial measurement gauge? Then you could measure it exactly, by positioning the tool or parts of the machine against the dial gauge…
You could write some simple g-code to move the cutting tool and then measure the position.
I like to use a dial gauge. I’ll place a piece of 1/2" stock in the collet and zero it out against the dial gauge. Then run the z axis for laps around the table or whatever you want and then run it back to 0,0 and see how far of the dial gauge says it is.
If you do not have a dial indicator, you can use sound as an indicator instead of you eyes.
Mill a slot in a piece of Wood. Move the running millingtool forth and back in this slot with equal or incremental distances. When you hear the mill hitting the end of the slot, you know its has passed the position where it was last. So with some clever movements and reading your software movement values, you can do mostly the same as if you used a dial indicator.
Dear Akhil, the repetability of the positioning is simple to determinate.
Take a dial gauge, atach it firmly to the mobile part of the axis you are checking. Atach, also firmly, an object to the fixed part in relation with the axis checked, expozing a flat surface to be touched by the gauge. Move the checked axis until the probe of the gauge tuch that face. Let the gauge’s probe be charged a little (minimum some tenth of mm) set that axis and the dial to 0 (zero). Move the axis to certain distance and come back with a GCode like ‘G00 X0’ and write down the dial indication. Do the same for several times. The values you’ve noted down will reflect the repetability of positioning for that axis.
Regarding about the precision of positioning this is another question. It is much more complicated/costly.
You have to determine if the studied axis moved the exact amount you command by GCode.
For very short movements, it can be done with a dial gauge with a reasonable run. This kind of instruments has a very short run. Tipicaly, for a 0.01 mm sensitivity gauge, this run is 3mm. So if after the first positioning against the fixed piece, you will command a very sort run of the axis, you can measure it on the same dial. But it is a little irelevant to measure the positioning precision on a 2mm run from a total of, maybe, some hundreds.
For that, you have to get a special instrument like a DRO. You shuld align it with the measured axis and check on it the effective displacement, against the one ‘ordered’. The difference is, in principle’ the positioning error of the system. But beware, the DRO, itself, has a measuring error. A ‘decent’ to be used is around few hundreds of dollars…
I am prety sure that one of our friens here, can imagginate a lot of scenaries with (maybe) less expensive equipment, but this is the simpliest way. Simply but a little costly.
Anyhow, for 95% of usual applications I wouldn’t be concerned about the positioning error but the repetability.
Good luck!