This article describes and analyzes the findings of children's observation records of block play with a focus on the wide range of mathematical outcomes resulting from children's block play. To this end, children's mathematical learning was analyzed in five areas: set and classification; pattern and symmetry; number and arithmetic; comparison and measurement; and geometry and space. It is found that symmetry accounts for the biggest proportion of mathematical concepts articulated, followed by attribute features and comparison, and graphic feature recognition. In comparison, children performed poorly in the categories of arithmetic, pattern expansion and creation, and measurement. Based on the performed analyses, it is found that investigating the types and frequency of mathematical knowledge that children acquire through block play is helpful to clarify the value and significance of block play in facilitating children's mathematical learning.