With　the　development　of　5G　and　the　enrichment　of　application　functions,　applications　have　put　forward　higher　requirements　on　the　computing　power　of　terminal　devices.　To　improve　the　computing　power　of　terminal　devices　for　applications　and　reduce　the　processing　time　of　tasks,　for　the　mobile　edge　computing　environment,　a　task　offloading　method　based　on　edge-cloud　collaboration　is　proposed,　and　a　Priority-Based　Chemical　Reaction　Optimization　Algorithm　(PCRO)　is　designed　to　make　offloading　decisions.　The　results　show　that,　compared　with　the　Genetic　Algorithm　(GA)　and　the　Chemical　Reaction　Optimization　(CRO),　PCRO　can　shorten　the　processing　time　of　tasks　and　obtain　better　resource　allocation　strategies.