Early Childhood Caries represents the most prevalent childhood chronic disease, and is one of the leading causes of premature deciduous tooth loss so we restore tooth function by zirconia crowns, prefabricated zirconia crown brands vary in micro leakage, surface roughness, and fracture resistance. Aim: to evaluate Hardness and Surface Roughness of Two Primary Esthetic Crowns (Nu-Smile and Elephant pedo crown) before and after Thermo cycling process to prove which is more durable and recommended to be used commercially. Methods: Twenty four specimens were tested; and divided into 2 groups (anterior and size 5 from labial surface): Group (1) was represented by twelve Nu-smile crowns (NUS®-crowns) made of zirconia ceramic (DentaCarts*). Group (2) was represented by twelve Elephant crowns (Elephant® crowns). Made of highly translucent zirconia (Bibodent*). To study the effect of crown type and aging on hardness and surface roughness of Nu-smile and elephant pediatric crowns; t-test or an equivalent nonparametric test was used for comparison between groups. Results: The difference of roughness NU-smile crowns, before and after thermo cycling was statistically significant p value=0. 001, the difference of roughness Elephant crown, before and after thermo cycling was statistically significant p value=0. 001, the difference of hardness Elephant crown, before and after thermo cycling. Was statistically significant p value=0. 001, There is significant higher roughness score before thermo cycling in elephant crowns compared to NU-smile crowns p=0.0001 .Moreover there is significant higher roughness score after thermo cycling in elephant crowns compared to NU-smile crowns p=0.0001. There is significant higher hardness score before thermo cycling in NU-smile crowns compared to elephant crowns p=0.01 .While there is no difference in hardness after thermo cycling in both crown types p=0. 99 Conclusion: The Nu-smile crown is more durable than the Elephant crown, the surface hardness of the Nu-Smile crown is higher than the hardness of the Elephant crown before and after the thermocycling process, The Surface roughness of the Nu-smile crown is less than the roughness of the Elephant crown before and after the thermocycling process.