it is too big and occupy disk space when photo number is big.

You cannot disable the cache as that stores all sized images you theme may need.

How much disk space is being used? And how much is that space costing you?

albums has about 35 GB,and cache has about 10 GB,is that normal?

Yes, since the images are cached. How much depends on the general image sizes and the quality settings.

So, really not much storage used for caching. So why do you say it is too big? Would you prefer to spend an extra second of processing for each image displayed every time your site is visited to maintaining the 10 GB of cache storage?