Crude oil is a product owned by your company and will be sold. Hedging can only be short (worried about falling prices) and short 900 lots of crude oil futures.

My idea is that if the spot price drops by 0.9 yuan after six months, then the futures price drops by 1 yuan after six months.

After 6 months, the spot loss 1000000*0.9=900000 yuan, and the futures hedging spot will get X* 1=900000, so x is 900 crude oil contracts.