Can niosII-32 run from 16bits datas width SRAM?

of couse, it can.

You could even run it from an 8 bit RAM chip. Bear in mind that performance will suffer, since the Avalon bus will have to make several RAM accesses to get each 32-bit instruction word.

I have made a test program using 32bits on-chip memory to run simple printf("hello world") include in the main() function, it works fine, then only change 32bits on-chip memory to 16bits on-chip memory, others are not changed, it can not work, why?

There's nothing that should prevent you from using a memory that has a data width narrower or wider than 32 bits. Be sure, however, to pass the byte enables out to the memory, since this is how Avalon will control which bytes of the data are relevant.