I'm using proteus but i'm finding it troublesome. can u please suggest its alternative for complex ARDUINO circuit simulation.
There's none that I know better than a breadboard.
There is not simulation software as such to simulate and entire project. Simulators like LTSpice are there but are used for simulating small circuits like RC filters and small logics.
You will have to do it on a breadboard like how it should be done and then use cad to draw the circuit and do a prototype by PCB etching and if all looks good send it to the FAB house.
That's how its done.
can u please suggest its alternative for complex ARDUINO circuit simulation.
Learn how to code and how to do electronics, a simulator can never be accurate for everything you want to do.