Kent decided on the change after the West Indies announced they had arranged a two-Test series against Sri Lanka, which would have kept Hooper, an influential all-rounder, effectively unavailable for the English season until mid-June.
Strang, 26, who caught the eye against England in Test and one-day cricket this winter, is to join Kent in mid-April after Zim- babwe's commitment in Sharjah.
Derek Ufton, Kent's chairman, said Strang had impressed him against England, adding that Hooper would rejoin for 1998.
Gloucestershire are resigned to replacing Courtney Walsh, their captain, who is also likely to be required by the West Indies.
Kent have awarded a testimonial to Alan Igglesden, their England fast-bowler, for 1998.