While I do know that Hongyi pao(European cannon)and breech loading guns were used by the
Qing army(and the lighter guns made by Jesuits), I wonder what kind of field pieces were used in wars against
the Dzungar Mongols in 1696, and the muslims of Tarim basin in 1759.
Guns lighter than the ordinary guns might have been used for such long-distance campaign,
but I do not know this precisely. The only source I have on this part is the picture below.
(The field pieces look like crouching tiger cannon)

Both the Qing and Galdan/Tsewsan Rabdan's Zunghar armies took to the expedient of mounting the cannons on the back of (Bactrian) camels. The illustrations of the time suggest that these were about the size of smaller field pieces (my guess would be about 5 pounders) whereas the larger pieces (8-12 pounders?) would be towed by a team (2) of horses. The proportion of the lighter camel mounted pieces to the horse drawn one as shown is 5:1.

I can scarcely imagine that one could load, aim and fire the camel-mounted cannons except that they are indeed depicted as such in a battle formation so it's not just that cannons would be carried to battle on camels and then dismounted for firing. Presumably even unaimed (and one-off - since one can't reload) fire of this kind could disrupt a closely formed enemy nit and give your side a temporary advantage to charge in etc.

Thank you for answering.
I wonder what the "Silk gun" exactly is. C.J. Peers mentions only
briefly in his Osprey book on Qing armies.

If you don't mind, can you recommend me some helpful sources on this topic?

Could you show here the picture with big Dzhungarian guns (8-12 pounders as you said) towed by horses? It is really very interesting!!!