Build a special odd tree model according with (*3+1)/2^k algorithm, to depart odd numbers in different groups.Carry out research into the tree,found that counts of elements in the tree reduce and converge downward one by one layer,values of elements converge downward to 1,and all odd numbers can appear in the tree only one time.Then prove the “3x+1”guess indirectly.At last,find a logic error of deduction of the tree,and prove 3x+1 guess in another ways.In the last section of last version of this paper,build a special identical equation,use its calculation characters prove and search for solution of any odd converge to 1 equation through (*3+1)/2^k operation,and give a solution for this equation,which is exactly same with calculating directly.And give a specific example to verify it,indicate that we can estimate the value of convergence steps n during some middle procedures.Thus prove 3x+1 guess--Collatz Conjecture strictly. Some supplements:The last section is not very detailed due to time,i think omitting part is not hard and critical.we can fully use characters of odd multifying 3,and no more +1 interference again.To build model for estimating steps n,we can use characters of formula (3) is bigger than corresponding part in formula (2),but should avoid trap:when converge to 1,steps can still increase forever.Add convergence condition:if highest bit of t(i) is 2^k,k should be odd,then all steps n>=1 can satisfy with the equation,i say n>=4 in paper is just want enough parts in formula (2) can appear. Some more supplements:watch t(i),its odd part add corresponding odd produced by odd x calculate directly in each step through (*3+1)/2^k should exactly be 2^k;watch 0 bits in odd part in t(i),because of characters of odd multifying 3,it should shift right or bit-count reduce in each step,and its weight in total t(i) should reduce step by step till to 0,when odd part converge to 1...1.Build weight model:value of all 0 bits in odd part/2^(2k),which 2^(2k) is corresponding part in each step,then model value should reduce step by step,could not exist loop!and model value can and must converge to 0,because obviously there is not possible to exist a convegence value,which its corresponding odd part in t(i) is not 1...1,and its model value can remain unchanged in next steps through multify 3 operation.Then odd part must converge to 1...1,could not diverge or converge to another odd.