Can child claim his medical expense even he is depend in my tax return?

No, if you are claiming your child as a dependent, you would claim the medical expenses on your return.  Your son cannot claim his medical expenses when he is claimed as a dependent. 

In order to do so you would need to Itemize your return. Medical expenses are only deductible for the amount in excess of 7.5% of your AGI.  So, if your AGI is $100,000, only your medical expenses over $7,500 will count towards your Itemized Deductions. Also, the total of all of your Itemized expenses would need to be greater than your standard deduction in order to get any benefit from your itemized deductions.  Itemized deductions include Mortgage Interest, State and Local Taxes up to $10,000, and charitable deductions.

Your standard deduction if you are filing as Head of Household is $19,400 and $25,900 if you are married filing jointly. 

learntofile,

The answer is maybe.

Medical expenses are itemized deductions claimed on Schedule A.  The instructions for Schedule A state:

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Whose medical and dental expenses can you include? You can include medical and dental bills you paid in
2022 for anyone who was one of the following either when the services were provided or when you paid for them.
• Yourself and your spouse.
• All dependents you claim on your return.
• Your child whom you don't claim as a dependent because of the rules for children of divorced or separated parents. See Child of divorced or separated parents in Pub. 502 for more information.
• Any person you could have claimed as a dependent on your return except that person received $4,400 or more of gross income or filed a joint return.
• Any person you could have claimed as a dependent except that you, or your spouse if filing jointly, can be
claimed as a dependent on someone else's 2022 return.

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So as long as your child paid for the out-of-pocket medical expenses, they are itemized deductions on their return.  On the other hand, if you paid the out-of-pocket expenses, they are yours to include in the list of itemized deductions.

Now as to whether it is worthwhile trying to claim them, that, too depends.  If your child's only income is from W-2 wages totaling less than $12,950, it is pointless to itemize as the standard deduction for the dependent will exceed his income and the taxable income is already zero.  In any event, the out-of-pocket medical expenses must be reduced by subtracting 7.5% of the child's adjusted gross income and that reduced figure plus typically state tax taken from paychecks and charitable contributions would need to add up to more that $12,950 to make a difference.

He can claim them if HE pays them, and that's unlikely if he is your dependent.

A dependent's  standard deduction, is the greater of $1150 or his earned income plus $400. It's rare, but sometimes a dependent is better off claiming itemized deductions