what are the course to join isro without jee advance .now i am ready to write jee ( now iam studying 11th in Tamil Nadu)

Besides Jee advance you can also give two more exams that work as a gateway to I.S.R.O

1.Through Kishore Vaigyanik Protsahan Yojana(kvpy)-It is a national level fellowship   program which is held every year so that students can pursue research career in basic sciences.
KVPY exam include two levels first is Aptitude test and second is interview round.
Candidates will be eligible for IISER(  Indian Institutes of Science Education and Research)admission on the basis of valid KVPY fellowship.
For further information you can visit this provided link: http://kvpy.iisc.ernet.in/main/eligibility.htm

2.Through State Central Board(SCB) channel:
eligibility-
Students who have passed 10+2 level with science stream in 2019 or 2020 are eligible to apply for admissions and appear for IAT 2020.
However, they will be considered for admissions to the degree programmes only if they obtain the cut-off marks specified for their board.
Students applying through SCB channel will have to appear in the IISER Aptitude Test (IAT) which will be conducted at various centres across the country.
The selected students will be able to get admission to IISER.

Other than the above options you can opt for these following courses to work as an I.S.R.O scientist.
~Courses In Space Science After 12th
B.Tech in Aerospace Engineering
B.Tech in Avionics Engineering
B.Tech+M.S./M.Tech (B.Tech. in Engineering
Physics + M.S. in Solid State Physics, Astronomy, Earth System Science/ M.Tech. in Optical Engineering)
M.Tech in Electronics, Electrical, Mechanical and Computer Science
PhD in relevant disciplines