AM radio Transmitter with one station DIY - microcontroller
My question is that for the receiver circuit, do i still need a tuner
  even though it is receiving only one signal from the transmitter?


Radio receivers use "tuning" so they can discriminate against those radio frequencies that they DO NOT want to receive thus, only allowing through the frequency of carrier wave that they DO want to receive.

You also need a demodulator to convert the modulated carrier back to audio/speech.