The boy was taken to Moranbah Hospital on Wednesday before being transferred to Townsville in a critical condition.

Police charged a 29-year-old Townsville man with grievous bodily harm and torture but his charges were upgraded to murder after the child died on Thursday.

A police spokesman said the boy was pronounced dead about 1pm Thursday after his life support system was turned off.

The 29-year-old was remanded in custody after appearing in Moranbah Magistrates Court on Thursday morning on the original charges.

He will face the Mackay Magistrates Court over the murder charge on Friday.

In a separate incident, police have charged a 33-year-old man over a string of alleged assaults on a two-year-old boy that eventually sent him to hospital.

The boy was flown to the Lady Cilento Children's Hospital about 3.30pm Wednesday after suffering critical injuries. He remains in a critical condition.

Police allege the man, from Kin Kin on the northern Sunshine Coast hinterland, assaulted the boy on "numerous" occasions from December last year to March this year.

He's due in Brisbane Magistrates Court on Friday facing one count of grievous bodily harm and four counts of assault.