Welcome to FT, yanguo47!^

The 500 mile minimum has sadly gone away, so it's unlikely you'd get 1000 miles credit. The question is whether your two segments are booked as one flight number or two. If it's one "direct" flight from A to B with a stop at C, you'll get the equivalent non-stop mileage from A to B. If it's two different flights, you'll get the actual mileage flown for each flight.