Pernille Munch, the prosecutor in the case, told Denmark's Ekstra Bladet newspaper that the man, who lives on the island of Bornholm, had partially admitted to running the DanBB webpage, whose members were required to communicate only in Scandinavian languages.
Danish police have so far extracted 56,594 images of child pornography and 3,174 video sequences from the man's computers and hard drives, but the total volume could be much greater.
As well as operating the DanBB site, the man was also an administrator of The Love Zone, a global paedophile network run by Australian Shannon McCoole, which was used by more than 1,000 paedophiles around the world.
Members of the global site had to submit new pornographic posts every week to maintain their membership, and could rise higher in the hierarchy depending on how much they submitted, gaining more access to the material.
Both sites were hidden in the “dark net”, with their users accessing them only through the Tor network, which hides the original IP address of users.
Bornholm Police raided the man's house in Feburary this year, seizing a desktop computer and hard drives with several terabytes of encrypted data.
According to Munch, some of the material shared portrays serious sexual acts with children.
The man faces up to two years in prison, and possibly more if he is shown to have committed the most serious crimes.
Norwegian state broadcaster NRK last year uncovered a Scandinavian-only paedophile site called Scandiland, also hidden deep in the 'dark net'.
In the Scandiland forum, paedophiles discussed their preferences and which sexual acts there would be willing to perform with children, depending on how much they resisted.