why in no load, the output only show the rectangular waveform. Is it to be pure sine wave after we applied LC filter?
i already got nice sine wave with pure resistive load.
You filter the output of the bridge (which you are driving with SPWM signals) using an LC filter and apply a load. Observe the output. And you should get a sine wave output.
Is it to be pure sine wave after we applied LC filter?
The output of an reasonably dimensioned LC filter (= the voltage across the filter capacitor) can't be a square wave. Apparently the measurement setup is wrong, e.g. viewing a bridge output signal single ended instead of differentially.
There may be other effects at no load, e.g. output voltage out of range.