In this talk, we will talk about two phase transiton results for quasi-Periodic Schr\"odinger Operators. 

For continuous Sch\"odinger operators with large analytic quasi-periodic 
potentials of two frequencies, we obtain the exact power-law for phase transition in energy.

For the almost Mathieu operator with any fixed frequency, we locate 

the point where phase transition from  singular continuous spectrum to pure point spectrum takes place, 

which solves Jitomirskaya's conjecture