Radio Netherlands said the painting's Swiss owners plan to use the proceeds from the sale for a children's charity.
The painting is one of the estimated 80 that Van Gogh created in the 70 or so days leading up to his death.
Emma Ward, a spokeswoman for the art dealer Dickinson, told Radio Netherlands "L'Enfant a l'Orange" is "a very cheerful painting."
"You see a small boy with long blond hair and blue eyes. He's sitting in a field with yellow flowers and wearing a blue jacket. In his hands he's holding an orange," Ward noted.
A reserve price of $30 million has been set for the portrait at the TEFAF art and antiques sale in Maastricht, which begins Friday.
A representative for the Van Gogh museum in Amsterdam said the museum won't be bidding on the painting.
"The painting doesn't have any priority for us. We're more interested in work from other periods," they told Radio Netherlands.