current direction under the other condition and situation
At this moment,what is the current direction?


An inductor cannot change the current in an infinitely small time else an infinite voltage is produced and nobody wants that. 

V = L\$\dfrac{di}{dt}\$ is from Faraday and encapsulates what I've said

So, at the moment SW1 and SW2 swap over, the current flow through the inductor remains the same and it has to find a path to continue this current. The only path is through C1 in direction B.


  Theoretically shoule be "A" direction


No it is not.


  Theoretically shoule be "A" direction, because the current direction should be high voltage to low voltage


Only the capacitor has acquired a voltage that can be sustained. The voltage across the inductor will be the voltage acquired on the capacitor prior to the switches reversing their positions.

For a capacitor, Q = CV hence 

\$\dfrac{dQ}{dt} = C \dfrac{dV}{dt}\$ = current

So, the change in current from being charged by I1 to receiving a different current from L1 results in a capacitor dV/dt change hence, the voltage rises or falls depending on the difference in those currents.

It rises or falls from the value it attained prior to the switches operating.