Translation:My uncle walked on the street.
Have a look at http://www.dartmouth.edu/~deutsch/Grammatik/perfect/Perfect.html , starting at "The Auxiliary Verb".
Short version: The verbs that take "sein" are mostly predictable on the basis of their meaning. They must satisfy two conditions: 1) they must be intransitive; 2) they must indicate a change of position or of condition.
why are using dative case "der strasse" when there is movement? shouldn't it be accusative "die strasse"?
The accusative is used with two-way prepositions when the place is the destination of movement.
Here, he is walking on the street but not onto the street. The street is the location of his movement, not the destination. Thus, auf der Straße with dative case after auf. (And note the capital S on the noun Straße.)