Can Shenzhen medical insurance be reimbursed for seeing a doctor in Beijing?

No, Shenzhen social security card can only be used locally in Shenzhen. If you want to seek medical treatment and employment in different places, you must first go to Shenzhen for medical treatment and then go back to Shenzhen for reimbursement. If you don't work in Shenzhen, you can transfer to your current residence.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.