reduce analog voltage for pic microcontroller

how to reduce 230V ac to 5VAC without using transformer?
is resistor droping method works here?

It depends on how you want to use the 5V.

First a warning - if you do not use a transformer you face a serious risk of electrocution. Resistor and capacitor votage droppers do not provide any safety isolation barrier, effectively you are connected directly to the 230v AC with all the dangers that implies. If you understand that, read on, otherwise use a transformer.

The value of the resitor in Ohms is determined by R=V/I so first you need to know what I is. V is the voltage you want to drop so its 230 - 5 = 225V. I is the number of Amps.
The power lost in the resitor in Watts as heat is V x I so it is 225 x the current you want in Amps.

You must understand that for a fixed resistor value, the voltage dropped is proportional to the current you draw through it, as the currnet increases the voltage drops and vice versa so you may have difficulty if your circuit current is not constant.

Brian.